rpm changes when "hot"

[3bears]

so first , its not really when hot. Its when its been running a long time. If Ive been driving say a half hour or more and say at a near constant speed, my rpm will go up about 200 rpm then go back to normal
or will drop down about 200, then back. then fine for about 15 minutes , then do it again
last night driving for about 1.5 hours it did it several times for about 5 minutes, then not at all for the last 15 minutes of driving.
No lights, half tank of gas. Plugged it in and no codes.

About 3 months ago I cleaned the maf, the throttle body, the IAC, replaced plugs,pvc, fuel filter...all preventative

between 30 and 40k ago (not at the same time), with previous owner and at the Toyota dealer, it had new belts, water pump, MAF, plug wires and plugs

have seen no power losses, still getting about 19 mpg

today I need to replace my alternator ( reason I drove to my sons) and picked up a new fuel filter and I'm going to clean and check all electrical connectors ( alternator makes noise when hot, like a bearing)
still throwing 14 volts, wonder if its related
btw,,,,doing the 140 amp alternator upgrade


any ideas whats going on ?

 

[3bears]

time permitting...checked lots of "stuff"
Bet its the TPS
symptoms very much like my x-wifes Volvo...which was the throttle body...which has the TSP built into it, and you cant just replace the TPS on those without replacing the hole throttle body
Volvo = $$$$$$$$$