I have a 2002 dakota 3.9 with an automatic. I just noticed when im doing about 60 down the highway with cruise control on that the rpms jump up about 200 rmps every few seconds and then kick back down. it is really noticeable. could this be the cruise control module going bad. i did put new plugs in last week before the problem started. they are bosch platinums. could the plugs be the problem? the whole issue started after i put them in. any ideas would be helpfull thanks!

 

What type of Bosch platinums did you put in? The regular ones or the +4 models? The +4s are not recommended for trucks, and have been known to cause pinging and misfires [:'(] Bosch platinum plugs in general aren't the best for a distributorless ignition system, as they tend to wear out more quickly and can often last only 10 to 20,000 miles. [:'(] Autolite makes a much better platinum plug line that seems to hold up to the constant firing of a DIS. Champion copper core plugs are also a good choice. The champion truck line, while costing slightly more, is also an excellent choice.

What did you gap the plugs at before you installed them?

 

the plugs are just the normal platinums, not the +4s. the gap is .040 also. someone mentioned that ut could be the TPS. what exactly is that... thanks

 

You could try re-gapping them to .035 or .038. From what I've heard, the 3.9 Magnum doesn't run so smooth with the stock ignition when they're gapped above .038 [>:]

TPS = Throttle Position Sensor

Here's a stock definition for you...as I can't put it any better than it does...
It is located on the side of the throttle body. It's common for them to get dirty and cause idiling and shifting issues.

 

That 200-300RPM "surge" is likely the torque converter clutch locking and unlocking. Whoever told you about the TPS being the possible problem is right on target. It's pretty common for them to cause this.

I'd replace the Throttle Position Sensor (TPS) if I were you.

 

I'm having the same problem with my 01 ram. But it happens when im in park also. Have you solved your problem? If so please help me.

 

Champion plugs are the best way to go in my opinion, I have them in my truck right now, no pinging knocking or nothing. If your TPS was dirty or not reading right wouldnt it set a code?

 

I had a hypertech 180 thermostat but was getting a trouble code for my engine running to cold. Do you have the same problem?

 

Not necissarily. They only tend to set codes when they stop functioning. And in the TPS' case, it usually sets a VSS code as well. [:'(]