2002 Chrysler T&C throttle bouncing up and down

This car has 145K and transmission was replaced 3 years ago with used one that had 75K at 105K. Since replacement 3 yrs ago it runs great in the winter, when cold and no humidity, and runs extremely bad when it is warm and humid. This summer was hot with no humidity (in Kansas) and ran great. Now with fall and humidity back it is acting up again. The rpm’s will show a jump up and down (300-500 rpm) while driving at 55mph or slower and do the same while at a stop light. At 70-75 the rpm’s do not change but you can sure feel it at 55mph not looking at the rpm’s move. Dealership has put it on computer and it shows nothing. It clunks and thuds when driving slowly and sounds hard on the vehicle. Any ideas … dealership has seen it once in each of the last 3 years, cleaned fuel lines, then filters … ect…ect… ect… and not helped more than a couple of days. I have made appointment with independent mechanic later next week.

Good Description, But Lots Of Things Can Cause A Driveabilty Problem As You Are describing It. A Comeptent Mechanic With Modern Diagnostic Equipment And Skill Set Is The Way To Go.

Is this a trusted individual ? Rather than describing all the symptoms to the mechanic, I’d offer to let her/him drive the vehicle home from the shop and back the next day if you can be witthout it.

Driving it cold and at operating temperature will give the technician the information needed to proceed in a proper diagnosis and any onboard diagnostic equipment from the shop that can be utilized will be of help.

Some of the 01 and 02 Chrysler T&Cs had problems with faulty throttle position sensors and the symptoms were more prevalent at colder temperatures, but this is just as wild a guess as many would be. Guessing and “throwing Parts at it” is not the best way to handle it.


thanks common sense … chrysler mechanics have seen it and put it on diagnotistic equip. but nothing shows up … will take to new mechanic ahead to let him drive it. it is difficult to drive in traffic and i would not trade a car like is in or it could be dangerous to the buyer.


In all of that stuff that has been done in the yearly visit to the dealer were spark plug wires ever included? I’m going to assume so but if not, have them replaced.

I was also about ready to say that it sounds like you have an issue with your mass airflow (MAF) sensor. But I don’t think these engines use them. I think that they use a manifold pressure (MAP) sensor only. In either case, these are the devices that are responsible for telling the computer about the air intake situation & engine load.

I’m thinking of these things because your variable here seems to be humidity. The thing that makes the most sense is moisture messing with electrical signals. Nothing else makes much sense.

A reasonably good mechanic can probably sort it out fairly quickly with use of a scantool. This is one kind of “hooking up to a computer” - but that can mean multiple things.

thank you … humidity and heat does seem to be my biggest issue. thank you for your input.


spark plugs and wires were replaced at 100 … dc301