I have a 04 STX supercab, 4.6l, ~135K miles. There is a fairly short steep hill near my house that I get some pretty high revs out of. While I go up it I usually start at ~20mph and get to ~40 at the top. When I get to the top my rev's get pretty high and the engine starts to shake until it shifts (my stock STX doesn't have a tach so I don't know what revs it gets to). Also, when I'm at highway speeds and I take my foot off the gas it starts to shake a little bit but the second I even touch the gas peddle it goes away. My initial guess is my torque converter is bad but figured I would ask before I do anything. After I get back from my vacation next week I'm going to take it in and get the tranny flushed and see if that does anything.


Any other recommendations?

 

So I got the tranny flushed and it seems to have helped the up hill issue but not the coasting at high speed issue. Yesterday I did some driving around and it is really bad when I coast at about 60 (fastest I went on the 50 MPH road is was on) but it still does it down to about 40. As a test to see if it mattered what engine speed it was at I down shifted and nothing changed. Then I shifted into neutral and still was getting a bad shaking. I assume if it was a torque converter issue it would have stopped in neutral. I'm thinking maybe a U-joint in the drive shaft or maybe the slip yoke? anyone have any ideas?

 

Service the rear diff. Check the pinion seal and bearing on the front of the diff.

 

How would I go about checking it?


Thanks for the input

 

Check for leaks around seal, check for play in pinion bearing by pushing up on yoke.