Jeep: transmission slip&jerk& check engine light is on, jeep cherokee sport, throttle position sensor

Question
QUESTION: Hey Chris I have 97 jeep cherokee sport 6 cylinder. lately my jeep sometimes jerk's when I drive ! And when I put it on park. the r.p.m. arm will go to  2 and that sometimes happens  also when my foot is on the break at the stop light . this      will happen for a couple of days ! then it will stop... and also my check engine light  has been on for about four years!!! machainics say that its just my computer  chip.
ANSWER: Wayne,

The AW4 trans in your XJ is nearly bulletproof -- with the exception of a very rare shift solenoid problem, most problems can manifest as what seems to be a trans problem, but in actuality is in the engine system. From what you described, I've had TPS (Throttle Position sensor) issues that caused this exact issue, particularly with the RPM surge. The absolute first step is to get the CEL (Check Engine Light) diagnosed by a reputable shop that will give you more information than "it's a computer chip".

Ironically, there is TSB#18-08-98, which refers to a CEL condition having to do with the TPS circuit. You can visit the local Jeep dealer for the update.

Good luck!

---------- FOLLOW-UP ----------

QUESTION: Thank you very much for responding Chris. Chris I had forgot to tell you that my jeep is a 2 wheel drive i dont know weather u knew that or not but you probibly did.and also chris   
I would like to know how much this problem will cost me? & I shure hope that it is not my transmission . thanks again !!!

Answer
Typically, if it's decided the vehicle needs the update, most flashes are done (at least at my shop) for .5 labor hours, while some have been known to charge 1.0 hour. Our shop was $90 at the time, so the bill was $45. However, this TSB should only be done if the tech deems it necessary.

Aside from that, most shops will charge an hour diagnostic time, and if it's easy to track down, the cost of the replacement part. Some might charge additional time for replacing the part, or if necessary, additional diagnostic time. The only way to find out is to get it diagnosed, and have them call you with an estimate before any other work is done. Most shops need 1.0 hour to start with, so that would probably be a minimum diagostic charge.

Peace!