Hello. My 1993 Ford E150 has been having a problem for almost a year now and seems to be getting worse. At any point hot or cold, I sometimes get a miss or stumble when trying to accelerate from a stop light. I can't get it to repeat when I want to, if it's doing it I can barely press the accelerator and it will take off almost normally but depressing it further will make it stumble more then it acts as if it catches itself and takes off great with full power.

Also, when starting it cold after it sits for awhile it will smoke black and smell like fuel and the engine will run a bit rough. It seems to clear up after it warms up Even after it warms up it still smells like it is running rich. At the end of the exhaust it is really sooty and black and any condensation that spits out as its warming up is black and sooty. It runs very rich every time I start it and runs rich even after driving it all day. Under load while accelerating to go up a hill it may buck or misfire every once in awhile.

Here are all of the parts I replaced thus far: Fuel pressure regulator, Idle air control valve, Throttle position sensor, plugs, wires, cap, rotor, coil, O2 sensor, air charge sensor, coolant temperature sensor, changed coolant and thermostat, pcv valve, air filter, pcv filter.

I ran sea foam through the brake booster and that made problems worse. After driving it to work it ran super rich all the time and continually smoked black all the time. Upon pulling the plugs I noticed cylinder number 8 was black and sooty while the others were not. Compression test was within factory specs. I changed the plugs again (now only have about 400 miles on them) and the number 8 plug is yellowish and the end of the threads is carbon black and the bridge is white towards the center of the plug. The center electrode looks like it is washed then heated several times as there is bits of carbon all around the electrode but not an even tan. The other plugs are whiteish in the center but they too look like they have been washed and are not an even color all the way around and have the carbon built up on the ring and is flaking off at some spots. I have also ran some injector cleaner through it several times to no avail, I don't think that stuff actually works very well to begin with though but I had to try it.

I did a fuel pressure test and get about 38psi engine running. 40psi engine off. It starts rapidly dropping when you shut it off, about a psi or two every 5 minutes. By the next morning I have zero fuel pressure. The van always starts right up and has never left me stranded.

I average about 10 miles per gallon even on the highway and I have gotten 14-15mpg on the highway over a year ago when I purchased the van.

I have no CEL and am pretty stumped at this point. Please any help would be greatly appreciated.

 

Forgot to mention, it is the 5.8l windsor engine.