Minor bucking/hesitation between 47-52mph

2001 GC with the 3.8L and 149k. Just recently noticed the under light throttle at speeds between 47 and 52 mph the van will start to hesitate, 'buck', or cut in and out for lack of a better description. The problem is easily replicated by finding a flat stretch of road, setting the cruise and waiting for the magic to happen. Gas mileage has been down and she requires more effort to start but I almost wrote it off as crappy winter blend gas here in Idaho. The first time I noticed it I could have sworn the dash lights were flickering as well but I've been unable to replicate that condition.

Newer parts include plugs, wires, alternator, battery, upper intake manifold gasket, fluid changes, front trans mount, Etc.

Nothing has been done within the last 8k miles or so and problem has just recently surfaced so I have a hard time thinking this is a result of something I did. I would suspect electrical but I'm not quite sure where to begin. Any help is appreciated.

Forgot to add, no check engine light or code that I am aware of unless there is a way to read 'soft codes' that don't set off the MIL.

i am guessing either ignition problem or fuel delivery. have you cleaned injectors lately?

I had a similar problem with a 3.3L caravan. After doing a bunch of work i had mysterious engine missing problems. One thing i did wrong was improper spark plug/engine wiring routing. I also replaced the spark plug wires and removed the intake plenum. When i reassembled everything i had a wire harness parallel to the spark plug wires that was to close. And were my spark plug wires went through the alternator bracket and crossed the alternator wire harness it was also to close.

Also if you remove the plenum then the fuel injectors get disturbed and the O-rings sealing them tend to crack and leak. If you use a rubber hose about 1/2 inch diameter you can listen to each injector for an air leak.

Haven't had a proffesional fuel service done but I run injector cleaner when I change the oil @ 5k miles. I'll have to do some poking around to verify wire routing and listen to see if I can hear anything out of the ordinary. I've also done a search and it seems some similiar problems were fixed by replacing the ignition coil...I know that hasn't been done so maybe I'll look into that as well. If any one has any other ideas or suggestions I welcome them.

i read on the 4g ram forum somewhere that they had a similiar problem. changing the coil fixed it.

Our 2001 3.8L has done this since the day it was new. It went back to the dealer at least 6 times for the problem with no resolution. I'm just used to it now.

If you've got a voltmeter, do a voltage sweep on the throttle position sensor. You should get a smooth change in voltage. Generically, most manufacturers will have voltages from .5 to 4.5 but Chrysler may have different high and low voltage values. The gas pedal spends most of it's life at a certain position and thus, so does the TP sensor. If you think about it, you're probably only using a quarter of the full gas pedal travel if you're not a maniac driver. Minor corrections to throttle for things like driving uphill still equals friction wear inside the sensor. The variable resistor in the sensor literally gets worn out and makes a weak electrical connection and the PCM may not be able to tell where the throttle is at all the time. Your cruise control does the same thing in acceleration and throttle adjustments. At the very least, you'll be able to rule out one problem.

Funny that the TPS was mentioned because two weeks ago, I replaced it on ours as well as cleaned the throttle body and the IAM. I was really hoping that after all these years, it would get rid of the hesitation but as it turned out, no luck. It acts just like a vacuum leak because full throttle works well but I've never been able to track down any vacuum problem.