I have a 1995 chev blazer with 4.3L W engine. it has a CMPI injector. I have replaced it four times for the same problem in two years. I thought maybe the computer was bad but replaced it with an used one and still have the same problem. It will drive fine for about six weeks to two months. Then the same symptoms return and get worse until it stalls and will not restart. It even drove well after taking the intake off and inspecting the injector/fuel lines and putting it back together without replacing a thing. It starts as a slight stumble at hwy speeds and progresses to cutting out completely. Please help me if you can!
Have you had it scanned for a trouble code ? You can get a free scan at autozone or similar parts store. There are several sensors that could be the cause of the problem. Or it may be a problem with the distributor/timing such as a bad coil etc. It does not necessarily have to be the fuel injection system.