Misfire when hot, replaced everything I could think of... Options

[cv7713]

OK, been chasing a misfire for quite some time. The car runs great first thing in the AM but misfires once normal operating temp is reached. Misfires at idle and while driving. First, I have replaced all fuel and ignition components and all vacuum lines. I decarbonized the combustion chamber (MOPAR CC Cleaner, good stuff!). I have replaced the MAP sensor, O2 sensor, and some various wires that looked corroded. Stock 5s-fe.

The engine bay seems to be getting extremley hot! (but not overheating). Yesterday I pulled the plugs to see if they show any evident signs of wear and I was confused by what I saw. The firing end looked great (brown to grayish color), however the insulator on top of the plug was brown and blistered (burnt)?! Anyone ever see this? They are NGK plugs with the factory heat range. Also (not sure if this has to do with the misfire) but every now and then I hear a pop come from my gas tank. Is the "pop" just releasing pressure from the tank? Is it supposed to do that? Sorry so long, I am just truly stumped!!

List of parts replaced:
Fuel Pump, Filter, Pressure Reg, Charcoal Canister, EGR Valve, and injectors
Brand new distributor, wires, plugs, igniter, O2 sensor, MAP sensor, and even the ECU!

Could this be a bad cat causing the heat? Cracked head? Thanks for input...

This post has been edited by cv7713: Nov 9, 2007 - 11:21 AM

[lagos]

can you describe "missfire" in more detail?
when you replaced your plugwires, cap and rotor, what brand did you use?

[supradog1]

can you describe "missfire" in more detail?
when you replaced your plugwires, cap and rotor, what brand did you use?

OK... i start the car up first time that day and it drive about 10 to 20 min car runs perfect... after this time frame the car is at full working temp, any time you stop after this time frame the car misfires whille idleing and during the launch from the dead stop... after 2k rpm misfire is gone but power is is week and gas mileage is crappy... also if you turn the bass up on the system the car misfires eaven more than before while idling!!! i have done full tuneup on celi inclueding autozone timeing belt, cam and crank seals, water pump, cap & rotor, bosh 02, ngk plugs and wires, puroltor fule filter, 93 oct fule with lucas fule additive, cleand egr system and replaced pvc, reset ecu and no check engin light... after tune up car runs good for about 20 min then misfire returns!!! put new ngk plugs in 3 times and dose not fix the problem!!! i am lost on this one, but i have also been told it could be the igniter... but i dout that because its eletronic and woud just fail altogether... right???