99 XLT strange bucking when driving slow

[ejbeach]

I recently bought a 99 Explorer and lately I have been having a strange problem.

When driving slow around 40ish when begin to accelarate to speed up, it start to buck or sort of studder. It usually does it about 3-4 times in a few seconds, then it shifts out of OD and seems to be fine. I am worried it is something with the trans, but it also seems like it may be the engine studdering. Runs great otherwise, it only does it when the engine is running slow and right before it downshifts.

It has 90,000 miles on it, and not sure if it was tuned up at all since i only have it a month.

 

[TPLYNCH]

Sounds like a tranny that's not downshifting properly. Does it feel like it is "lugging" like if you left a manual tranny in high gear when going to slow?

 

[monkeydude3]

could just need a fluid flush which would best be replaced with synthetic. Also check for TSBs

 

[Rhett]

It has 90,000 miles on it, and not sure if it was tuned up at all since i only have it a month.

Check the plug wires first. If it were me I would start by replacing both plugs and wires, if the wires are old.