Two weeks ago while driving i threw a service code p0302. Car drove fine but did a ohm test on all coils #1 and #2 cylinder were failing. Replaced them car drove fine for a day then started misfiring hasn't thrown a code. I replaced 2 coilspacks all 8 boots on the coil packs. Changed spark plugs car still runs like crap. I don't have any crazy mods. It's just a 2000 gt.I have 75mm plunum & throttlebody,K&n filter,magnapack,4:10gears. I only have 75,000 miles on the original motor. Don't really want to take thisto the dealer i have a feeling its somethingsimple.

 

the same thing happens 2 my truck i dont kno what it is...is there a really rough idle and feels jumpy and backfires...? thats what happens in my f-150 4.6

 

It idle rough has a harley type put-put sound 2 it. I was thinking that it might be the fuel filter don't remember when that was changed or if has ever been changed. I just don't know. What are the signs of a glogged fuel filter? and would a glogged fuelfilter throw a service code?

 

yea not sure...well if i figure my truck out ill let u kno and like wise

 

That is a tuff one, many people have had it. It could be alot of different things. 1, Fuel filter, 2. fuel pump, 3. TPS, 4. MAF needs cleaning,. Since you already did the plugs, and the coils. That is what I would suggest checking. I have the misfire, and I have done all of them exceptthe coilpacks. So that is my nexy thing. Good luck, and if you figure it out please let us know.

 

it almost sounds like timing is off, i worked on a car that was doing this, they had replaced the coil, wires and plugs, the fuel injectors were in working condition, it ended up being the timing was off by a good amount,

 

A month ago my dad's truck had the same problem, upon checking on his truck parts it turned out that his timing parts are failing and needs some replacement. Better check yours. I would also suggest (like what other members had said) that you check on other parts like that of starter, spark plugs, ignition coils,etc. better do a compression test or a leakdown test.

hope it helps. Good luck mate.