I just bought a '94 F150 with a remanufactured 5.0L engine with about 10k miles. The engine has a little stutter or flutter when it idles. The idle is constant and smooth other than the stutter or flutter ever second or two. I first noticed it while sitting at a stoplight. I can feel it in the truck. I also now notice the same feeling from the engine upon accelleration. If I take off easy I can hear the engine stutter some. It isn't terrible as you have to listen and can barely feel it in the truck. If I take off fast I don't notice this problem, though it may still be there and just not easy to hear/feel when talking off fast.

On a different forum it was suggested I clean/replace the IAC. I cleaned the IAC but there doesn't seem to be any change.

I do have a small exhaust leak which is behind the O2 sensor and cats. It is in some flex pipe right in front of a glass pack. I would say this leak is located about half way back in the exhaust system.

I have checked the vacuum lines but can't seem to locate a leake in them at all. I have run some injector cleaner through the system.

Any help is greatly appreciated. Thanks

 

pull codes, (www.fordfuelinjection.com) also check the timing with the spout connector removed it should be at 10* btdc. check the plug wires and routing to make sure none are touching or arcing (watch at night). your tps will usually cause the idle flux.