The idle and engine seems fine when not moving. But moves or accelerates slowly with hesitation. I have checked the fuel pressure (45), new spark plugs and wires, new air filter. New TPS, cleaned idle air control valve, cleaned throttle body, cleaned MAF sensor. Once it picks up speed acceleration is good and strong. Especially troubling since there is a depression at the gate and it Boggs down. The revs climb slowly but no movement! At idle engine idles smooth and seems to rev/race, fine/normally. The wheels lack the ability to spin wheels in mud, even though it is 4WD.

 

You didn't say anything about the fuel filter. How do we stand with that?

 

A few years ago while trying to fix this same problem I managed to tear off the grey plastic / Teflon pipe going to the fuel filter because the quick disconnect fitting had got damaged prior to ownership. To summaries, I took it to a mechanic who fit a different housing with a new filter and it did not cure the slow pick up in speed.

 

It would help if we knew the year, model, engine size and mileage.

 

I got two like my alias. Both are 1999 with the 4L V6 SHOC engine. All wheel drive, 5 speed automatics. The one with the slow take off is an XLT has 60,000 miles and the one I compare the performance to is a Eddie Bauer.

 

There is one thing that comes to mind and that involves the torque converter. The stator in the torque converter is supposed to stay stationary so that when you give the engine more gas it is supposed to multiply the torque. It sounds like it is free wheeling . You might consider to get a second opinion on this from a good trans shop. The worst it could involve would be a torque converter replacement If you decide to go this route, the diagnosis would be appreciated by a lot of folks here, thanks.

 

I had a feeling it might be the transmission and did do a auto fluid change, I could not change the filter since I was sent the wrong ones (twice) maybe for the 4 transmission not the 5R, but I checked the o rings on the auto filter and they were fine. On the stator you mention, in the torque converter I will look into that.

I am not sure when the problem developed, since I had a nasty rattle on my higher mileage Eddie Bauer and did all the 3 timing chains, right left and front jackshaft. Since this low mileage XLT also had a less severe rattle I just had it done on the front jackshaft since it does not involve removal of the engine, I think it might have developed then or maybe it was when I last did a transmission and fluid change and had the same effect, I opened the cover to see and the new filter o ring was torn and used the old filter's o ring.

I will go to an Automatic Trans place and check on the Stator. Thanks.

 

Just to let everyone know the poor acceleration problem has been solved, after my Explorer failed to start a couple of weeks ago. The machinic put a new fuel pump!
Since my brother drives it I have not been able to determine the true end result.
The only persistent problem now is the slight grabbing in the transmission at slow speed/crawl, again I have not thoroughly driven since the new fuel pump.