2003 Sport Trac hesitation/jerking?

[jcattau]

2003 Ford Explorer Sport Trac XLT v6 4.0 with 89k.

Hey all, lately my truck has been acting funny. About 1 out of 3 times I start my truck and put it n reverse it starts doing what I would describe as a hesitation. If I sit for about 10 seconds, it will stop. But if I move while it is happening it will move and jerk as if i was slightly hitting the break constantly (no the parking break is not on). It will continue when I throw it in drive until I give it some gas. From then on as far as I can tell there are no problems. It doesn't do it everytime. I went in for an oil change and they told me I will need to replace the belt soon, so could that be the culprit?

If you know anything, let me know about how much it will cost me.

Thanks folks.

[shorod]

This could be due to several things. It could be as simple as a dirty throttle plate, it could be a vacuum leak, it could be an ignition misfire, it could be a dirty MAF sensor element, or it may be a failing Idle Air Control (IAC) servo. When you are driving the truck, particularly under load (slight hills at highway speeds, etc) does it stumble or sputter? How's the fuel economy? Does it seem to only do this when the engine is cold, or is it all the time?

Do you know if/when a tune up was last performed on this truck? If you don't think it's ever had a tune up, you might invest in that now. While checking the air filter, consider removing the MAF sensor from the air intake tube and clean it with the MAF sensor cleaner spray. While there you may as well remove the air intake assembly and clean the throttle plate as well.

-Rod

[jcattau]

Thanks for the response shorod.

It doesn't stumble or sputter, and since it does it on startup I would assume it happens when the engine is cold. The fuel economy seems normal. Again, it only starts when I throw it i reverse, not just starting the truck.

The guy before me who owned it was an older man who took very good care of it, so I have to think there was a checkup or two done to it (I bought it with 72k on it).

[shorod]

In both of the posts above you specifically mention reverse. If you start it up when cold and put it in Drive will it also do it, or have you not tried that? If only in reverse it would point more towards a transmission issue. If it also will do this in Drive, then it could still be a transmission issue, but it's more likely an issue with the engine, maybe an Engine Coolant Temperature (ECT) sensor issue or IAC issue.

-Rod

[jcattau]

It only does it in reverse. It will continue to do it until I shift off of reverse. So I can shift it into N or D and it will stop. If I shift back to reverse it doesn't do it.

I'm really confused as to what this could be.