Ok I have a 1990 with a 4.0 and auto trans. I have a issue that has me stumped. It spitters and sputters like one cylinder is missfiring. The only time it does it is sometimes on a hard start, and when I am going up a hill at a slow speed(under 20mph) and I give it some more gas. If it starts doing it and I floor it, it sputters a little then takes off like nothing is wrong. I have replaced plugs, wires, distributer cap, rotor, fuel filter, and even pressure tested the fuel line. Any ideas? I searched the forum and could not find anything with the same symptoms. It will not do it under normal driving, just under the above stated circumstanses. Any help will be greatly appreciated.also I forgot to add that if sitting in park it will not do it. but if you put it in drive and hold the brake while giving it gas it will do it. It sorta sounds like when you first crank a chainsaw or weedeater and you go to give it gas and it bogs and sputters.

Thanks,
Lurch

 

ok here is a update, I have checked all the vacuum lines and pluged or replaced a few, and today I installed a new MAP sensor. It is a little better, not doing it as often , but still doing it. Any ideas???

Thanks,
Lurch

 

fuel injectors maybe put some good addative for this in tank on next fill up