1988 7mgte idling around 1k normaly it'll burp and drop to 7 or 800. when I'm wot I can feel it hesitating like a missfire. It also look like when I hit the throttle real quick I'll get a burp and my narrowband o2 gauge reads lean. What in the hell do I check first? I didn't store any codes, and my fuel filter is brand spankin new.