Hey guys, my '88 245 B230F has been running a little rich for a while now, but up until recently it wasn't an issue.
All of a sudden though, it's causing me problems. The car idles fine, but you can sit at the exhaust pipe and watch fuel spit out in little sprays. Every so often the idle will skip and it'll bounce right back, but it still does it. If I park on a dry surface and let the car idle for about 30 minutes I can come back and there will be a spray pattern on the ground. Again, though, at idle, runs great.
But when I put it in gear, a whole 'nother story. I park on a hill, and the first thing I do when I get in my car is reverse up said hill to turn around in my driveway and drive away. Putting the car in reverse, then applying my foot gently to the pedal to drive, the car bogs down and starts to spit and sputter. It will move, but it doesn't like it. When I come to a stop in reverse, before I shift the car into drive, sometimes it will idle down and die. Always starts right back up though. Once I'm up to speed, the car runs awesome, but I don't really have passing power. But at say, 60MPH, everything is gravy. I can accelerate to keep speed up a hill. But like I said, there's that low speed hesitation, and if I put the pedal down, it doesn't really do anything. The car actually backfired on my way to work today at low RPM.
A little backstory on maintenance. In July, I replaced plugs, wires, cap, rotor, and AMM. Replaced the flame trap in January, and the thermostat and radiator hoses in February. Did the alternator in February as well. Car has roughly 330k and I've driven it maybe 10,000 miles since doing the tune up.
The car has been really reliable, and has made several 300 mile one-way trips since I bought it, but this recent cut in fuel economy is killing me.

The theories I have currently are:
Timing is slightly off?
Fuel pressure regulator is going bad and dumping fuel?
Leaking injector?
Fouled plugs?
Failing AMM?

I can't check anything until tomorrow afternoon, but if anyone has any insight it would be really awesome. I love my brick, and want to do fun stuff to it, but can't stand this 15mpg crap when I'm normally getting almost 30.

 

timing wouldn't make it run rich.

check the vacuum port of the fuel pressure regulator, when the diaphram fails, fuel squirts out there. check the fuel pressure.

does that car have a 5th cold start injector? try unplugging it.

fouled plugs is a symptom not a cause (sure, once they are fouled, it doesn't help anything).

a dead AMM causes the car to run in a fall-back mode, open loop, where it runs rather rich, and the throttle lags quite a bit. if you shut off the car, unplug the AMM, and restart it, and it behaves pretty much the same, chances are pretty good your AMM is bad. shut off car, plug back in, restart to double check no change.

a failed O2 sensor makes the car run rich, too. you can slip a thin wire into the O2 sensor data connector pin, and use a digital volt meter (+ on that wire, - on ground, DC Volts), with the warmed up engine idling, a good o2 sensor will go back and forth somewhere around 0.3 and 0.7V every couple seconds. an older one will do it a little slower, maybe 10 seconds per full cycle at an idle. the frequency speeds up if you rev the engine til its several times per second and hard to see on the typical DVM.

 

Some more information.
The car now idles like ****, and if I hit the brakes too hard it dies. It's consistently backfiring under load and there is an audible vacuum sound near the intake manifold.
I pulled the spark plugs, and three were white (lean) and the fourth (at the firewall) was coated in oil, and there's a **** ton of oil on the outside of the hole around the spark plug. My theory is that I've got a toasted piston ring and I'm blowing oil into my combustion chamber at an alarming rate.
I replaced the vacuum line between the manifold and the flame trap, and wrapped the flame trap tube from the top of it to the intake pipe with electrical tape because I was not satisfied with its seal. I replaced the line going between the large check valve at the top of the intake manifold, and the black tee beyond it. I also wrapped the large piece of hose with electrical tape because it was cracked as well. I checked all other vacuum lines and they looked/felt good. Most have been replaced recently. It almost sounds like the intake manifold is leaking, and as cheap as the gasket is I went ahead and ordered it.
That all being said though, I think my issue is blow-by and I'm boned. Opinions?

 

compression test. if #4 is way off relative to #1-3, then yeah, you got a mechanical problem there.

oh. oil OUTside the plug is due to valve cover gasket leakage.

 

you mentioned white plugs, which yeah, is lean. very lean can burn holes in pistons

air leaks downstream from the MAF, like in the plastic air ducting, the throttle body gaskets, or the intake manfold, or the injector seals will make for lean burning.

 

The thing with plug #4 is that the oil appears to actually be coming from the hole itself. It's actually dry above the plug.
And the plug itself, is completely covered in oil. From the hex bit down is completely oily.

 

Does this engine have the distributor running off of the rear of the head? If so there is a rubber oil plug that blows out if the flame trap gets plugged. When this happens you get oil all over the rear of the engine and down over plug #4. If it isn't the cam cover gasket then look at the rear of the cam. What is the compression of #4