Thanks for help - ONE MORE QUESTION!

Thanks for your help in diagnosing my pickup to this point. Your diagnosis have been great.
I at least have the bad boy running again and going down the road, however
one problem still exists that I can't seem to fix!
1991 (actually 1990) Ford F-150 with 5.0HO .302 motor
As we last talked, I was having a stalling problem, which appears to have been a coolant blockage, causing an overheating condition that the sensors weren't picking up. The ECM must have been shutting the motor off detecting a problem.
All is fine, except for a minor issue. When driving down the road, this truck now runs like a champ. When you come to a stop at a red light, stop sign, or even brake slightly at low speeds, the motor tends to idle low. The tach shows an idle speed of ~500 RPM. I would assume that reading is low. The truck never stalls (well, occasionally, but it is not that big an issue, just happens in the driveway where you were not at a high RPM coming to a stop) and it keeps on going even with the A/C on. However, it sure feels like it is going to stall.
The TPS seems to me like it might be the sore spot? Is there a way to test it?
My buddy suggested that I unhook the battery to reset the ECM and it might find the idle at a better spot, but that didn't help.
Any thoughts as to what is going on here? Thanks in advance!!!!!

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