what would cause the truck a 94 GMC Sierra stall out
If the CEL is on, get the codes scanned first. It could be any number of things. For example, bad MAP sensor, Bad MAF sensor, bad CPS, dirty throttle body, dirty IAC, on and on. The code should give you a place to start. You can post the codes here and someone will tell you what they mean.
Check crankshaft position sensor....
Looking for a Used GMC in your area?
CarGurus has 199,871 nationwide GMC listings starting at $895.