acceleration problem

[hank91]

I recently replaced a head on my 91 Ford Explorer 4.0 liter engine due to a blown head gasket. Now the engine starts up fine and begins by idling smoothly in the driveway. Then, after about a minute, it starts to stumble then shudders, catches itself and again idles smoothly. When I begin driving it will not accelerate properly for a couple of blocks but then kicks in and runs fine. What could be causing this?

 

[jd4242]

Did you replace it with the same head,90tm? Check all vac lines and spark plugs and maf plug.

 

[hank91]

I replaced the head with a new one as the old one was warped. I've checked all the spark plugs and vacuum lines. What is the maf plug?

 

[jd4242]

Mass air flow plug.sounds like a fuel problem,fuel filter been changed?

 

[hank91]

I did not change the fuel filter as I could not see any reason as to why changing out the head would have related to the fuel filter. I was thinking that the problem is somehow related to the fact that the engine overheated when the head gasket blew thereby perhaps damaging some sensor.

 

[jd4242]

not really any sensors that would get hurt by overheating on a 91.did you replace both heads,were they new,what was the model number on the new heads.does it do it all the time?plugs are new right?

 

[hank91]

I only replaced one head with a new one as the other one seemed to check out ok with my pressure test and did not reveal any wet plugs. I did not replace the spark plugs, I'm using the same ones as before the gasket blew.

 

[jd4242]

I would start with some new ngk plugs.sounds like a plug fouling out or gas problem or sticky new valve.or you could have gotten the wrong head they make 5 different ones all that fit a 91ex