88 I6 MJ will not kick down and go when mashed to floor!

The past two days when i drove my MJ when i would mash the throttle to the floor (like getting on the interstate or going up hill) there was no go to it. it would not go over 55mph on the interstate mashed to the floor. climbing hills on regular roads it would not go over 45mph. it has never done this before. you cant even tell that there is anything wrong until you have to matt it to the floor.

Ii bought a multimeter and adjusted the TPS to specs of 4.2V and that did not fix it. but i have figured out that it will rev corectly when manually put itno 1-2 and when you move it to 3 it starts to bogg down. then when you put it into D it just stays bogged down and wont let it kick down to go. when you start off in drive you have hardly any power from 0mph and up.

what could this be? it has a brand new cat with like 2000 mi. on it.

thanx

anybody???

Check your detent cable (the cable that hooks into the throttle and controls tranny shifts) I am not sure if there is one on the MJ. I had a 90 Chevy Lumina Eurosport that had the same problem and the solution on it was a stretched detent cable that needed adjusting.

I am comparing apples to oranges here but I thought it could give you another idea on what to check.

ok thanx man

Don't just check to see if the cable is attached at the throttle body linkage- follow the cable down to the side of the transmission, and see if the tranny side didn't get cut or pinched. Either end being bad will kill the kick-down.

Does it have the comfort sport mode switch? Mine will act like that if it's in the comfort setting. I always leave it in the sport mode.

Check that the TCU has power. I believe on an 86, the fuse in on the wiring harness just before the TCU, which lives under the right hand side of the dash. If the TCU does not have power, the tranny will give you 1st gear is (1-2), 3rd gear in (3) and 4th in (D). That is assuming you have an AW4.

i had this problem with my 87 when i first got it. i'm not 100% sure what fixed it, but no single thing seemed to completely obviously do it for me. i changed the trans fluid and filter, probably made the biggest difference. I also put in a new tps. I adjusted the kickdown cable, and also all of my stock dash switches were sticky, i clicked them on and off a bunch of times and they seem to be cleaner and working better now. i know the sport/comfort switch to the right of the steering column was not working at all, but is now. hope that helps some. it worked for me, i can accelerate now