Highway oddity

Some strange behavior today on the highway; I think I know what it might be but wanted to consult the AF community first.

2000, 4.0, 42RE transmission, 95K miles.

Going down the highway at about 70, cruise and AC on. Suddenly the transmission shifted 4-3, back to 4, then alternated a couple of times. I hit the o/d lockout, it stayed in 3rd for a couple seconds, then the engine died. During this time the speedometer was varying between maybe 30 and 80 or so. The tach was also moving around, but I think it was the result of the shifts.

I put it in neutral, restarted, then it was fine after that for the 30 miles I drove to get home. I then recalled that about a week before, it had hunted in the same manner between 1 and 2 when leaving a stop light, twice that same day but never again after that -- until today.

I'm thinking it's the speed sensor somewhere, but would appreciate thoughts/comments.

Wow you're all over this forum too. My 02 did that and it ended up being that the tranny was about to take a dump.

Jason

Ug, I hope that's not the case. It's throwing the P0320 code, which indicates bad crankshaft position sensor, so hopefully that's it. Other than the episodes listed above, the trans has been fine.

If it is throwing the CPS code, you should probably go with that. Eventually, it is going to die completely and probably not start or run very long.

Bryan

Yep, and thanks. From looking at a lot of other posts here, that seems to be the progression. I'll have it in in the next couple weeks probably.