I have a 98 gt....it has about 111k on it...It runs great when you are into the throttle but when you are just keeping speed it wants to misfire in a sequence.....its not a random misfire...i can almost time it when it misfires its about ever 2 seconds and i cant figure it out....i replaced the intake manifold, plugs wires, ran injector cleaner, ect ect and still does it....i ran thru the vacuum lines and found one that t's off and has a rubber cap on it....i have no idea where its supposed to run to? Also i wonder if it may need the fuel injectors cleaned out????

 

if its in sequence it sounds to me like its in one of your cylinders. since its got alot of miles it could be one of your spark plugs may have some oil on it. my old car was misfiring alot and i checked the plugs and sure enough they were covered in oil. i cleaned them and voila no more misfire. if you have access you can try to pull the code and see which cylinder is misfiring.

 

Well the deal is i had just changed the plugs about 70 miles ago and wires....and still same problem.....the guy that had it b4 me had like 3 diffrent sets of plugs and some junk wires on it...i went ahead and did all motor craft....for about the first 5 days it had a really bad idle and would hardly run...all that cleared up and now its just that misfire....ill pull the plugs and take a look....only thing is...the check engine light wont come on

 

thats strange. is there any possibility of one of the spark plugs being defective or installed wrongly? because if its a misfire and it happens at the same intervals its gotta be a particular cylinder isnt working right. does the misfire get faster as you speed up?

 

No it doesnt.... its only like when im about a 16th into the pedal....only when im keeping the speed limit not accelerating

 

then im stumped [>:]maybe something wrong with the computer? no idea. sorry bro. hopefully someone else comes through.

 

thxs for the help next step is going to be the injectors and ignition

 

U need to get a computer code rather than replacing all your compenents it might be cheaper in the long run.

 

Well i would if it would send a code :/

 

you already tried to read the code? cause with older mustangs alot of the bulbs in the cluster like to go out. so if your check engine light isnt comming on then it could be the bulb is out. in fact, last night the bulb behind my tachometer died so now i have to go by the sound of the engine when i drive at night. anyway take it to someone that can pull the code and it should say where the misfire is comming from. its also a good idea because it may not be a misfire. the more i think about it the more i think it may not be a misfire but something completely different. once your car gets passed that 10 year old mark anything can happen. trust me. lol. i dealt with sooooo much crap with my older 96 GT.