i have a 1995 GMC Sonoma and i just changed the fuel injectors and the head gasket and the O2 sinsor and when i accelerate the engine loses power it has an manuel transmission so i know its not the transmission but it had some valves that were kinda beaten up but they would still seat good. also my check engine light comes on too but it dont come on till you drive the truck for about 10-20mins. what could be worng with the truck. it has a 4cyl 2.2lt engine if that helps.