The fuel pump is in the fuel tank so not really exposed to engine heat. Try the test jumper. If it helps, you have narrowed down the cause and if it does not work, you have eliminated the AFM and Circuit Opening relay as causes. It is an easy test to do and my theory of troubleshooting is to do the easy tests first then move to the ones that are harder to do as you narrow down the problem cause.

I think your right. I printed off your page on the afm and its values on resistance. I could see maybe a heat related problem with the afm, since its in the engine bay, vs a problem with the fuel pump. Going to check it out tomorrow.

Okay, I drove it around awhile, actually burried it over the front bumper in mud, back end sticking up in the air. Anyway heated it up good while being yanked out by a ford ranger. Turned it off let it set about 15min, and like clockwork the problem started. First I tried the wire jumper, it made no difference. So, I did an ohm check on the Afm here are the results. E2-Vs was 460ohm which is over the 20-400 range. E2-Vc was within range E2-Vb was with in range. Then E2-THA was 1617 ohm which was with the afm being warm to the touch, probably about 70deg. which is out of the range for that temp. Then I let it set for a bit longer and rechecked. Everything was the same again but E2-THA now I had nothing at all when I checked it.? Tried to drive it, started up fine, Idle was rough and it sputtered and bogged if you try to drive it. So what do I make of this ? Whent back out after truck was completely cold, and checked the range on E2-Vs, It was now at 615 ohms which is even further out of the 20-400 range. And was still getting nothing on the E2-THA pin. BUt the truck is running fine?

What do you think 4crawler?

Not sure what the tolerance si on out of range AFM resistances at the ECU. Suppose you could swap in another one and see if that changes things.

Kind of expensive to replace if Im not sure if its the problem. I guess the question is can heat cause the afm with problems to mess up, then after it sucks enough cold air, begin to function normal? Thinking about putting a fuel gauge on to see what the fuel is doing when it starts acting up. Does the afm on the toyotas tell the fuel pump how much fuel to send? if it does then a bad fuel pressure could be both the fuel pump or the afm telling the fuel pump the wrong thing? It does this problem every time like clockwork. Did it last summer for a couple months, then stopped and didnt start up till first of Jan. and has done it ever since.

Test when cold.
Test when hot.

Readings change from OK to bad, then your answer is yes.
Used AFM from a junkyard is not that much.

AFM tells fuel pump to run (or not). Fuel pressure regulator and engine vacuum tell what pressure the fuel is at. ECU tells injectors how much fuel to inject based upon AFM, TPS and O2 sensors among other things. http://www.autoshop101.com/ tech articles are a good read.

Just checked the afm with the truck completely cold, with it starting and running fine. E2-Vs pin was still out of range and and the E2-ThA was still open, which its not supposed to be. But everything is running fine.
Could the fuel pressure regulator cause a heat related problem?

It is all mechanical, but a pressure gauge would tell you.

What about the TPS? When the problem is acting up, if you punch the pedal to the floor it jumps and accelerates just fine, but as soon as you let the pedal slightly off the floor it starts stumbling and bogging.
Does the ECU go into a closed loop( no readings from 02 sensors) when you go full throttle? My cobra does, just didnt know if my truck functions the same way.