89 Blazer S-10 4.3 EFI. It starts fine when cold and warms up normal. But when warmed up it seams like it runs lean and stops,I can get it started again and it will drive some then but seams like it is lean. One other clue is The service engine light comes on when cold, but when it warms up it goes out and then I have the problem. I have replaced the fuel filter and the O2 sensor but neather has helped. Any one have any ideas?

 

Could be lots. Vacuum leak, fuel pressure could be lower then specified (9 to 13 PSI for TBi). Injectors could be dirty and not spraying on a good pattern. Use the paperclip method to get your codes (if any) and report those to us.