I've checked then timing fixed all of the vacuum leaks, cap and rotor are new the wires seem fine and the plugs are new, it has a new fuel filter, I changed the IAC and it doesn't stall anymore. The only thing I found that was weird was spark plug for cylinder number 4 was black and the others were clean. I tested the EGR and its fine, I can't figure out for the life of me what to check next. For whatever reason the idle also stays high until you put it in gear. Its not a bad miss but you can tell its not right and its down on power there's also a bit of popping coming from the exhaust

Sounds like that spark plug isn't firing. Sometimes they're just bad. A black coating on the tip is caused by unburnt fuel. That popping in the exhaust us the unburnt fuel igniting from coming into contact with the hot exhaust pipe. You will notice the same thing with very rich running performance cars. Put that plug in a different cylinder and see what happens. Could also be a compression problem. How many miles are on it?

Edit to add: Is the plug gapped correctly? Should be at 0.56. The plug could have also been fouled by too much fuel caused by a faulty injector. Swap the plug and wire with another cylinder and see what happens.

[This message has been edited by RilesOfSmiles (edited 12-27-2013).]

Mileage is unknown the dash shows 112k but something is making me think the motor has been swapped out, I've had an all original 1984 duke with 170k on it and it was less of a mess than this, but my choices were keep fixing my rusted into the ground fox body or get another car I actually like. I'll get some spark plugs tomorrow I think it has some NGK platnums in it for some odd reason not my first plug choice for this motor, I had some bosche platnums that did really well though

Year of cars/engine w/ problems? it matters.
See my Cave, Duke Quick Ref

1 cyl then do a compression test.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

[This message has been edited by theogre (edited 12-28-2013).]