92 B2600i stalling out

I have a Mazda B2600i 4 cyl. 4x4. The problem it has is that I can start it, and it will idle, but after a few minutes if I put it in gear and try to drive, it will sputter and stall out. I have changed the ECM and TPS and that had no effect. Any Ideas?
Also...is there a trick on this truck to get the
error codes from the computer without a Diagnostic Tool (eg. blinking check engine light)?

Thank You

Check your fuel filter.