Hey I just got a 1995 mighty max. I passed the California smog test the other day but now my check engine light turns on for a few miles than back off for a few miles. If I turn off the truck when the light is on, it's still on whenever I restart the truck. But, it will turn off after I drive a bit. It doesn't seem to come on when just idling. Any ideas about what might be happening? I don't have the manuals yet... hopefully today I'll get them and also a multimeter to check the ecu codes. Thanks yall.