Ive done that with car not running then running. Loads on and off. The readings get lower and lower from cold to operating temp. I havent tested around when it starts to shut down which is about 15 to 20 mins. But when I go to work and park my car I turn on a load such as my efans or blower motor and everything shuts down

Update.,new bat alt and belts and it still dies with an electrical load after hitting operation temp

I was talking to one of the techs at my job. Told him the story about my car from the begininh. Jumped my bros car the around the time I got my supra. That same day my coolant temp gauge stopped working. 2 techs heard that and gasped and said I might have fried my computer

Unlikely... EFI relay or fusible link are more likely and should be inspected.

"Techs" from where?

Cavalier ford. And you know which pin outs are for the ground circuits so I can at least I can do the voltage drop test

Those dealership auto techs are always such drama queens... Unless... I hope you're not just talking about the lot techs. ;)

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/

It was 2 of em. But it would make sense. I found a guy with the exact same issues as me on a different forum and I msged him and now waiting for a response. That is the 1990 so I didn't think it would apply to me but u notice that the ground wires are white and black so is it the same for the ecu

There are very few differences between pre89 and 89+ GE electrical systems... unlike the GTE. You may go by that online manual and if you get hung up due to a discrepancy just ask.

I suspect either a bad EFI relay or a bad AFM. Try testing them both after heating them up with a hairdryer. ;) Another possibility would be a problem with the fuel pump relay and resistor pack. You can bypass both at the harness to test if this is the case.

I tested the air flow meter based on the haynes manual a while back and it passed. And would a relay cause the whole electrical system to do this?

And this guy had the same problem as me. http://www.supraforums.com/forum/sho...0-Voltage-drop

Haynes/Chilton suck. I've got a ton of factory service manuals from a dozen different auto manufacturers and I've yet to come across one which is as poorly written as those two companies' offerings.

I posted a better means of testing the VAFM than what is specified in the Haynes/Chilton and TSRM just the other day: http://www.toyota-supra.info/forums/101981-post10.html You still need to test the FC switch (VERY important to pay attention to as it's a complete cutout switch) and the temp sensor as prescribed in the TSRM. The FC switch or its wiring is another possibility.

The load specific behavior of the failure isn't decidedly characteristic of a faulty EFI Relay or Circuit Opening Relay but they're simple enough to test and their failure may cause intermittent cut offs.

I don't recall you mentioning having tested them yet, but test the 100A fusible link (the old wire type used in earlier models will eventually corrode to the point of becoming a crippling restriction in the electrical system) and test the relay and resistor pack for the fuel pump.