Equinox Problem

The engine light comes on, not the services engine light. After diagnostic they said dirty injector and to run injector cleaner and if that doesnt work then the injectors need to be blown out. It runs fine then it starts to
sputter and **** then fine then it starts again. It seems to happen in the 40 to 50 mph range. It starts fine and runs great till this happens

I work for a GM dealer we find a pile of cracked plugs in Equinox's causing the problem you describe, most of the time it is cylinder 1, 3 or both
if this is the problem replace the plug and ignition wire. Might be a good Idea to replace all plugs and put a new wire set on milage wise your getting close to tuneup time.