Intermittent problem driving me bonkers

[TheRealNap0le0n]

So I've been chasing this problem for some time now...

Symptoms:
*Wont idle, or if it does it surges from almost 100rpm to about 1000rpms until it dies
*Black smoke out of the exhaust when free revving
*When accelerating car runs seemingly fine and has power but emits black smoke
*When cruising the car runs choppy even surges
*When I let off the gas while accelerating the motor/car decelerates faster than normal, feels like i have the brakes on or feels heavy in a way
*When it idles it has a intermittent light pop

I've changed:
injectors,
injector o-rings,
the plugs, wires, cap and rotor
by-passed the knock sensor
Fuel Pressure is around 35psi running with vacuum to the regulator.

The wierd thing is the car will run absolutely fine one day and run crappy another, or even have "mood" swings with in the same driving trip.

[Hijacker]

Moved to the 240 tech.

[moso]

if you changed the injectors and o-rings i would start by taking off the fuel rail and making sure none of them are leaking, have someone key on and off the ignition to prime the pump while you watch the injector seats for signs of leaks. after that I would go directly to the ecu and check it for codes. post back let us know what happens.

ps. i assume you have a stock ka24de

[Chris28]

Yeah check the codes, if they show nothing don't be afraid to pull the cover off the ECU and look for anything visibly wrong.

[4cefed]

Sounds like MAFS to me. I can't remember if the engine runs in this car with it unplugged. Try that, it should run generally rich and not-so-smooth, but it will be consistent. Swap it out with a known good MAFS.

Edit: try a new coolant temp sensor if that doesn't work.