1999 Rodeo/Passport strange transmission issue

I have a 1999 Isuzu Rodeo LS, 2WD/V6/Automatic (same vehicle as a Honda Passport, so I have crossposted to both Isuzu and Honda) that has a strange transmission issue. I want to know if anyone has ever seen
anything like this, or has any suggestions.
Every so often, with absolutely no warning, frequency, or anything causing it, the Rodeo will start shifting very rough. It will buck when switching gears, either upshifting or downshifting. Most time shutting down the Rodeo and leaving it for about 5 minutes will cause it to start working normally again. Sometimes the issue will happen when I first start driving it, other times it happens while I'm driving it - I may be driving along fine, come to a stoplight, and when I start going again it will start shifting rough.
It has about 91,000 miles on it. I just replaced the transmission filter and fluid and that didn't make a difference. Right now it's running fine, so I'm not about to take it to a repair shop until it starts happening again.
The strangest thing is that this also happened with a car I had previously (2000 Saturn LS2). The transmission shop couldn't find anything wrong with the transmission, but suggested I replace the Throttle Position Sensor. That is only sold with the throttle body ($300+) so I ended up living with the issue and trading it in before it was fixed, so I don't know if that was the cause of the problem in the Saturn or not.
Thanks for any and all suggestions, Jake Williams Madison, Alabama
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snipped-for-privacy@elcomsales.com wrote:

Hi Jake .... I had this happen on my 2000 Trooper. It turned out to be a faulty mode/range finder switch. An OBDII analyser may read a P0705 DTC.
Swicth was replaced under warranty and the problem hasn't recurred now for about 2 years.
Hope this helps.
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Thanks for that advice. Were you getting a check engine light or anything like that to lead you to hook up to the OBDII? I have not tried that yet since I've never gotten a check engine light. I will have to do that next time the problem surfaces to see if it reads anything.
Thanks, Jake
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snipped-for-privacy@elcomsales.com wrote:

Jake, No warning lights came on at all. The CEL will only light if there is a problem that can affect emissions. It was the dealer who plugged it into the tech2 analyzer and found the code.
One other thing that can hint at the mode switch being a problem, is that the transmission selector lights on the dash might jump around between positions if you just bump the selector slightly with the palm of your hand.
Savvas
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Update after two weeks and a 400-mile trip: the problem appears to be fixed. I read this FAQ: http://isuzufaq.ibctech.ca/#faq59 which agreed that it was the range sensor. That page links to a PDF with step-by-step instructions for removing and cleaning the range sensor (or you can just buy a new one). The sensor was a mess inside, you couldn't see the PCB in there and the contacts were all covered up - cleaning it has made the transmission act perfectly.
Thanks, Jake Williams
sav wrote:

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