1992 GMC Sonoma engine kills

First of all thank you very much for your donation.Let's start with do you have any code's?

have code reader but all it does is make the service engine light flash on and off.
how do i tell if ECM is bad?

It's supposed to flash that's how you get the code's.I emailed you instruction's on how to get the code's to your personal email.Let me know what the number of the code's are.

fallowed your email - all it does is make the "service engine" light flash on and off.

It's suppose to flash you count the flashes you should get one flash then two quick one's that's a code 12 it will do that 3 time's then if it goes one flash then two quick one's for a fourth time then you only have the code 12.I doubt your ecm is bad since you said it ran good for 10 mins when it's cold.Let me on the code's and we will go from there.

sorry about that- didn't read my deractions completly.

OK it keeps giving me "12"
my friend told me to try changing the EGR- done that - no diff. Starts great, runs till it gets to running temp, loses power starts to miss a little then dies.

Ok just a code 12 no help there they all flash out code 12 that's normal.Alright here's what you need to do next when it die's and won't start check and see if you have spark.If you have spark then we need to check for fuel pressure they rent fuel pressure gauge's at auto zone for free you just leave a deposit.Let me know what you find with those two.