shakes and studders between 45-55 mph

[explorer37]

I have a 1998 explorer XLT 2wd 4.0 with 167000 miles. The tranny was replaced at 99000 miles. It has started to shake and vibrate (best way to describe it is it feels like you run over a rumble strip for about 1 second) when it shifts into and out of overdrive. It seems to be coming from the area right under the drivers feet. It also studders between 45 -55 mph under a load. I have replaced the plugs, wires, maf, iac all within the last year. I am thinking the studder may be fuel related but am unsure. Any help would be appreciated with these problems

[Indy Tech]

Originally Posted by explorer37

I have a 1998 explorer XLT 2wd 4.0 with 167000 miles. The tranny was replaced at 99000 miles. It has started to shake and vibrate (best way to describe it is it feels like you run over a rumble strip for about 1 second) when it shifts into and out of overdrive. It seems to be coming from the area right under the drivers feet. It also studders between 45 -55 mph under a load. I have replaced the plugs, wires, maf, iac all within the last year. I am thinking the studder may be fuel related but am unsure. Any help would be appreciated with these problems

The whole truck is shacking and vibrating or the engine.
If its the truck ,check your drive shaft U joints.
engine, check engine mounts. just an idea