stumbling on acceleration
 

My wife 2002 Mountianeer with 66K, awd, v6,and auto stumbles when I try to accelerate while moving. EX. if I am driving about 45mph and I try to increase my speed, the car stumbles or shutters for a second or two then it accelerates fine. I don't have a check engine light on, yet.
Any ideas what could cause this problem?
Thanks,Jay

This start all the sudden? I have had two similar situations.... Water vapor in your fuel lines could cause stumbling. Have you tried a dryer like Heat?

I had a 99 Ranger with a 3.0 that stumbled off and on for months while I chased my tail around. Problem ended up being crap in my fuel injectors. In this case I ended up cleaning some with carb cleaning and re-installing, and replacing 2 that did not read in the normal resistance range (you can check this with a multi-meter if know what resistance is suppose to be).

Fuel filter changed recently? That is another easy possibility.... Good Luck!

All I can say is... "Red-Line S1 Complete" fuel system cleaner! Good Luck!

Actually, two of my vehicle at one time would stumble, and both had the same issue, a dirty/fouled MAF sensor. If the MAF element can't give you accurate information about the amount of air going into the engine, the computer will not add enough fuel, causing lack of power and stumble/hesitation. As the airflow increases, the inaccuracy is still there, but becomes less significant or noticeable.

Hows your prev maint doing? Cleaned throttle body valve recently?

Here is where I'm at. I'm trying to change the gas filter,BUT, I can't get the gas line off on the side that needs the tool to remove. I have the tool, BUT I just can't get it off. There must be a trick. Help!!!
Also, what is the correct way to clean the throttle body? Can I just spray it or do I need to remove a sensor first. Help, i'm in over my head.
Thanks, Jay

Remove the big rubber air inlet hose. Spray carb cleaner on the valve just inside the body. Use your finger, flush with the cleaner. Do the front, the edge, and do the back side. Spray on up inside the body. You'll be amazed how dirty it gets. I lay rags on the serp belt so the cleaner won't contact it.

Thanks, Steve. I'll give that a shot.
Has anyone tried Seafoam on there intake? If so, which vacuum line did you use, or does it matter?
Also, I changed the fuel filter. It may have been the OE.
Thanks again, Jay

Jay, Srercrcr was right on with the TB. I spray the crap out of mine every once in a while and always get tons of dirt out.

Using that fuel filter tool can be tricky. Every time I change one it takes me a couple tries to get then apart!

Don't feel overwhelmed! Nobody on this board started out knowing how to make repairs. Most learned like you.... Had a problem and went after it!

Update
 

I changed the gas filter and the car runs about 95% better. I'll clean the TB this weekend. For now, we're off to friends for a traditional new years day dinner of pork and sauerkraut.
Happy new year to all.
Thanks for the help and support, Jay

BEEE CAREFUL which spray you use in the intae on the throttle body. MAKE SURE you only use a spray safe for Mass Air Flow Sensors.

Did this to my Taurus and wound up damaging the MAF. Immediately got the check engine light with codes. Had to replace MAF as regular carb cleaner damaged the MAF.

Has anyone tried seafoaming? Ive tried that with good results.