Previous owner parked the vehicle for 2-3 years. I am starting this thread to chronicle my progress and hopefully to receive helpful input from experienced enthusiasts.

I had it towed to my driveway where I put in five gallons of premium gas mixed with sta-bil, changed the engine oil & filter, removed the spark plugs and squirted Marvel Mystery Oil in each of the 4 holes. I turned it over a few times with the starter and let it set up for a couple of days. Judging by the plugs, the vehicle was running rich when the previous owner retired it.

I spent the next two days exterminating the four mice that were living in the tire tool storage area and vacuuming / blowing out hickory nuts in various nooks and crannies...including the breather box. So far I have not found any chewed wires (grateful).

The next day, I gave it a basic tune up. Air filter, plugs, wires, distributor cap, ignition rotor, flame trap, and cleaned the throttle body & MAF sensor. I went ahead and put a thermostat in for good measure. I didn't want it to overheat on my first go
It started up after three tries. It sputtered a moment and then began idling...too high and surging. Advancing the throttle caused it to backfire, blowing the hose to the intake from the idle air control valve off. Nasty looking smoke poured out of the tailpipe. After warming up fully, I was able to drive it under the carport where I could work on it. I also found the forward gears seem to work fine, but it does not engage very well in reverse.

 

Still running rich (all four plugs), idling too high and rough, I started looking at anything having to do with fuel/air mix. Unplugging the MAF seemed to take the idle down, but it was still running rough, plus the resistance on the plug tabs according to my Bentley manual was off. With crossed fingers, I ordered a $79 aftermarket sensor. The new MAF seemed to calm the idle, as in slower and not as harsh, but it was still surging. I unplugged the small vacuum line from the fuel pressure regulator to the intake, and it was peeing gas...plus the idle stopped surging immediately. The joy of improved idle combined with the terror of gas squirting all over the motor was a new emotional flavor. I replaced the FP regulator with a new one from Autozone. Hopes were high, but it went back to a harsh and fast idle. The surge was gone at least.

Next, I turned to the idle air control valve. The resistance between all three electrical tabs was correct, but the valve itself did not turn freely. I pried the housing off and used PB Blaster to loosen the valve until it turned with the unit in hand at the flick of my wrist. The reassembled valve tested correctly according to the Bentley manual, but when it went back on, it made no difference. For the heck of it, I put a new aftermarket IAC on. It actually seemed to calm the idle down and smooth it out. I let it run a while. All of a sudden, the engine started idling up and racing at an alarming rate. After turning the motor off and back on a couple of times, it kept returning to this racing idle. I unplugged the wiring harness from the cheap MAF, and it immediately calmed down. I tried the original MAF, but the motor runs better at this time without either. Advancing the throttle causes a loss in power or a backfire until the motor is fully warm. That is where I am now. (note: This vehicle is missing the preheater hose from the exhaust manifold, so I don't believe my MAF sensors are being destroyed by heat from a stuck airbox thermostat.)

 

Taking a little break from the mechanical side, I removed the carpeted wood board from the rear hatch and doused the front carpet and leather interior with vinegar from a spray bottle. The interior is in great cosmetic shape, but it smells like rodent and mildew. The carpet will have to come out. I will try cleaning with tuff stuff, but it may be history.

 

1986 is in the bad wiring years (81 or 82 to mid 87)... beware of wiring with brittle insulation, especialy in the engine compartment. it often fails INSIDE the black plastic harness jackets, causing all manner of erratic gremlins.

 

So, if I unplug something and nothing changes, or if I plug something in that creates misbehavior, that is not necessarily a reflection on the integrity of the part.

I have a new MAF, IAC, and FP regulator. Each of these seemed to have made a difference. Any logical reason why the scary racing idle with the MAF plugged in, and a more acceptable idle without it? I have read warnings that aftermarket MAFs are often garbage.

 

I have tried unplugging the throttle position switch while running. No change. It makes an audible click immediately when the throttle is advanced.

I have also advanced the throttle with a screwdriver and blown cigar smoke into the throttle body via the IAC port. I could not detect any smoke coming out anywhere, but I got a sore throat for a couple of days from the cheap cigar.

 

i suspect your old one is dead, and your new one is garbage from what you say.

note you should NEVER hot plug them, always shut the engine off before unplugging or replugging the MAF, or you'll quite possibly fry it.

IIRC, new LH2.2 MAF's need to be adjusted. I think it requires a gas analyzer to do properly, although maybe it can be done from the duty cycle of the o2 sensor lambda circuit.

 

Adjust with the slotted screw next to the plug? Thanks for the advice...especially on the hot plugging. I will look up the adjustment procedure. Maybe the new one is just out of adjustment.

 

I found a link for setting the base Idle on my fuel system here.

Condensed version:
1.Check for vacuum leaks
2.Clean and adjust throttle body and check TPS
3.Warm up engine
4.Check and set timing
5.Check O2 sensor and replace if necessary (I will go ahead and replace mine due to the rich conditions it has been running.)
6.Adjust idle screw on throttle body
7.Adjust MAF

I will be backing up to #4.