my check engine light is on

HAVE IT SCANNED AND GET THE PROBLEM FIXED

If you take it to your local GM dealer they will have the proper scan tools to retrieve the codes that were stored in your computer- this will tell them what needs replacing (some common causes- bad 0xygen sensor, loose gas cap or corroded filler neck, etc.)

go to any of the major parts stores auto zone,napa,carquest,o'reilly's they will normally scan the codes for no charge then post again with any noticed problems

Fix the problem

If your check eng light comes on for a few miles, then does not, and it keeps doing that, it may be your Mass Air Sensor. You won't notice much of a difference in performance, but it does effect it. Quite the pricey little bugger, too.

Truck seemed like mother was running rough, shaking, and stalled.