Stalling/hesitation/no start
 

1988 740gle N/A
Hey all first post and stumped on my gremlin. Bought this car for $400 with a bounty of receipts. This car has been great getting me up north to see my son. Noticed slight hesitation at moments of acceleration. Tried paying attention when this happens such as going up hill,speed, readings on tach, amount of gas in tank etc.. Over the year it has gotten progressively worse. To where there doesn't seem to have any method to my madness. There was a point when I had looked down on my fuel gauge and it had peaked to full. Having me think "wow I can have that much gas in the tank"? Moments later the needle dropped onto empty. Speedometer also decided to rest on 0. Odometer and clock have also went on strike. Temp gauge moves but not entirely trusting it in fears of being in cahoots with its fellow counterparts. So far this is the list of work that I have done.
1. Fuel pump sending unit (wiring was deteriorating)
2.main fuel pump & filter (now making a weird noise)
3.new plugs and wires
4.ignition coil replaced
5.o2 sensor replaced (good thing too the bulb at the end wasn't there)
6.fuel relay switched out ( somebody wrote on it "fixed" and date)
7.intake throttle cleaned
8.intake hose replaced (very flimsy and oily)
9.air filter replaced
10. Cleaned PCV
11. Checked for leaks around intake manifold
Previous Owner Receipts
1.timing belt and harmonic balancer
02.bypass overdrive solenoid
3.ignition/ steering column
4.replaced secondary fuel pump & sock (towed in)
5.replaced fuel line @ regulator (towed in)
6.replaced:spark plug, wire, dist. rotor & cap
7.replaced battery (towed in)
8.replaced water pump & motor mounts
9.COMMENTS ON INVOICE "bogs & jerks going uphill or warm outside- smelling fumes running rich. Vehicle feels like it's misfiring, ohm out spark plugs wires all wires relevantly good. Check cap & rotor for arcing marks. No marks apparent. Check timing to see it was off set to 12 which is spec vehicle still runs like misfiring.
10. MAF (used)
11.PCV flame trap hose from PCV canister to intake pipe fuel pressure at 31psi (charged him 60 bucks for labor on this)
12.replaced MAF (new one by the look of the price)
13.exhaust manifold, 02 sensor, exhaust manifold gasket

So judging from the receipts this guy was trying to find the issue as well with little help from the shops he went to. Charging an arm and a leg for ten minute jobs not solving the issue. Leaning toward a wiring issue and have a part on order from ipd. It's the ignition control module aka ignition amplifier. Part on there is currently a usa manufactured. Going under the hood to clean my grounds and take a closer look at this zip-tie wiring harness close to the ignition coil and fire wall.
Any helpful ideas on where or what I should consider to look at. Plus it's leaking oil like the exxon valdez. Some gaskets eh? Thank you in advance for the responses that'll hopefully appear.

Volvo had issues with the engine wire harnesses that would degrade over time and cause all kind of issues. From what I've read those issues were fixed midyear in 1987. What month/ year was your '88 built? My '89 740 was built in September 1988 and has been a smooth runner for the 2 years I've owned it.

If your unsure about the condition of your engine harness you could carefully check some areas under the sheath convering the harness. Look for bare wires due to the insulation having deteriorated.

They missed one of the most common reason for rich conditions....fuel pressure regulator.

If you start the car in the morning and it starts and runs fine....let it idle for a while and then go and step on the gas, if you ten feel your hesitation and misfiring its your FPR.

The last FPR issue I had the car only started giving issues if allowed to idle. Once at idle for awhile the fuel would build up and you would start to smell it through the exhaust, at that point if I would try and rev the car it would spit and sputter until it cleared out. If I would start it and drive it right away it was fine but would have a small hesitation if allowed to idle for a little bit, a lot if I allowed it to idle longer, and if left long enough the car would die.

Update
 

Got the ICM aka ignition amplifier in the mail. Checked the wiring and did find a deteriorated power cable to the starter. Replaced that (fire hazard) with no improvement. Will be getting the fuel pressure regulator today. Fingers crossed.

Disappointed hope
 

Looked up this part number finding out it was a idle control valve. Had a lot of of build up and cleaned it up but made no difference. Guess I'll wait for the FPR to come in.

Replaced the FPR no luck sputtered out on me again could it be the cat? Some sort of pressure buildup or heat issue?