Check the steering shaft (located between the steering column and steering gearbox).
The section that is supposed to collapse has an injected molded rubber section that can become separated inside, causing excessive play.
So I kind of scanned through and didn't see that anyone answered your original question.
Yes, there is supposed to be 5v on the signal wire when unplugged. It's a carrier voltage.
The three pins on the TPS harness should test as follows, KOEO, sensor unplugged:
Pin 1: sensor ground, 0v
Pin 2...
clean the battery posts and inside the terminals with a battery brush. They need to be nice and shiny when you put them together. A dull surface is an oxidized surface, and oxidization does not conduct electricity.
Try changing the temp sensor.
My (completely stock) 99 does this too, sitting idling on a hot day with the a/c on, but I haven't tried addressing the issue other than checking coolant levels. I thought there was a bubble or something. Raising the RPM to 2500 rapidly drops the temps back to...
tread with caution. Depending on the consistency of the sludge, i.e. dry and chunky or smooth and creamy, can determine what you want to do. The creamy style can be easily cleaned away with a good oil filter and a quality additive like BG MOA or marvel mystery oil and several successive oil...