runs rough when hot

[94redranger]

Hey all my 94 4.0 runs rough when it is hot outside. In the winter time when it is cold it runs very smooth with no stuttering. When it is warm it stutters. It has new plugs/wires, O2 sensors. It does use a bit of coolant, but that seems weird that a bad head gasket would affect it because a crack/leak should expand and let air in/out regardless of the outside temp, cause the engine is always the same. Any thoughts?? Thanks!

 

[Big Jim M]

First thing

Hey all my 94 4.0 runs rough when it is hot outside. In the winter time when it is cold it runs very smooth with no stuttering. When it is warm it stutters. It has new plugs/wires, O2 sensors. It does use a bit of coolant, but that seems weird that a bad head gasket would affect it because a crack/leak should expand and let air in/out regardless of the outside temp, cause the engine is always the same. Any thoughts?? Thanks!

First you must find the coolant leak. THAT is more important than the stuttering. Sometimes it takes crawling under the engine with a flashlight.. But it is important to find the place where the coolant is escaping.. Allowing the leak to continue is risking the entire engine.
90% of all leaks start externally.
Big JIm

 

[Earl43P]

http://www.fordfuelinjection.com/?p=28

http://www.fordfuelinjection.com/?p=29


Those two temp sensors would warrant investigation.
The two wire coolant temp (feeds PCM, not gage).