My car will start but only run for 2-3 seconds.

This may be vats related.
I have tried different ecm's and different proms. Funny thing is I tried a prom from a '92 cavalier and it started and ran(albeit not very well, but it ran for 20 seconds)

I have plenty of fuel pressure, lots of fuel pressure and lots of spark. The injector pulse seems to get weak when the car is dying.

Is there a certain procedure to reprogram a VATS??

 

VATS only keeps the starter from turning over. What error codes does your ecm have? Have the chips been in dierect sunlight? Possibley a fuel delivery issue too... What is your fuel pressure? After all that you should have it narrowed down pretty good.

 

No error codes

I have lots of fuel pressure(checked at the rail and have a gauge in the car too)

I never thought of the direct sunlight thing, but I bought a brand new memcal from gm, so that ruled that out.

In the schematics, the vats takes fuel to the injectors and crank too.

Anyone know if there is a certain procedure to reset the vats?

 

There's a VATS bypass in the tech articles, and a lot of threads on it. You will have to pull off the driver's side kick panel to get to it. I wish i had schematics here. It would make things easier.

Here's a link for the VATS. It has everything you need to know about it.
https://www.thirdgen.org/vats

 

It wasnt a vats problem.

It was a grounded out throttle position sensor