ok. I have a 89 celebrity with 2.8 and auto trans.

Car starts and runs. The first start of the day makes the car run for a few minuites then stalls. But only runs for like 20 seconds each start after the intial start. I changed ECM and Fuel pump. Where should I look next?

hello,you're going to diagnose the basics 1st.when you get it to the no start
condition see if you have fuel/spark

It always starts. It just stalls every 20 seconds.

You need data... check the fuel pressure on the fuel line... it could be a fuel pressure regulator. See if you can keep it running by adding a bit of fuel to the intake as it's running. (Careful of the fire hazzard)

It could be the fuel injector, or it could be in the spark system (Coils/Module/CPS).