Expert: autohelp - 4/15/2009

Question
QUESTION: I recently bought a 91 Cadillac with the 4.9 engine. I had the car checked and the repair shop adjusted and cleaned the throttle.
A month later the car is now revving up and down while in park idling. NOTICEABLY!
The only codes that come up are the E91 and E97 and E98 which reset, but come on again later.
What do you think?
Thanks for your help.

ANSWER: When the codes appear, After each code there is the word HISTORY or CURRENT.

Which codes are history and which codes are current ?.

Do you know WHAT was adjusted ?.

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

QUESTION: All of the codes have been cleared, but frankly, I have checked this many times and never remember seeing "history" or "current". All I know is that they clear and show only 7.0.
As far as the work done, they removed and replaced the throttle position sensor.

ANSWER: OK. Then how many times does each code display. Do they only display ONCE such as : E91 E97 E98 70.

Or display like this: E91 E91 E91  E97 E97 E97  E98 E98 E98  70.





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

QUESTION: They display one time, go to the next and then E.E. then 7.0

Answer
E91 = intermittent fault in the neutral starter safety switch.

E97 = intermittentPark to neutral engagement problem.

E98 = intermittent ISC fault.

70 = End of code sequence.

What work or diagnostics of ANYKIND WHAT-SO-EVER have been performed on the vehicle trying to fix this problem ?.

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