Ok I have sc300 93 Lexus, I thought I had a fuel pump problems so I replaced my fuel pump and filter. (What was happening was once it was warmed up it the car would choke out and would not refire found flue pump had would not click on) So I replaced same problem after replacing so went a little further found that the computer was turning off fuel pump once I was warmed up. So now I ordered a re-built computer car cranked and ran fine for about 50-60 miles then started skipping and sputtering and reeving engine high. So sent computer back and they sent new one now it want crank at all can take the other computer re-install and it will crank just idles high. So after two computers is this still the problem or is there something that I am missing?

First, test the fuel pressure at the injector rail.

You state the fuel pump was being shut off when the car reached a certain temp with ECU #1. That is inconsistent with the statement "the car would choke out". I think what you mean is it died from fuel starvation. Did your spark plugs indicate a lean condition (really light tan color). Also, with ECU #1, it sounds like it was cranking fine. I mention this because you make a point of it cranking fine when you discuss ECU #2.

When ECU #2 appeared to fail, did you go any further into why the engine was skipping, etc.?

With ECU #3, the engine will not even turn over. Is that correct?

What codes were associated with the problems with each ECU?