I have a 90 L98 I just bought with a GM HOT cam, 1.5 rockers, siamesed lower manifold, LT1 injectors, headers, no cats. It previously had a much larger cam and had a custom chip burned for it. I thought it just need a new program, so I had a chip burned for my setup. All chips (stock, old burn, and my new burn) run OK until it goes into closed loop, then it starts to run bad, pops through the exhaust, and is really rich, undrivable. Set timing to 6* w/ ESC wire disconnected, set IAC and TPS to .54v. New cap, roter and coil, O@ sensor last summer. It runs pretty good (though still rich) until it goes into closed loop, so I don't think it's anything mechanical. I have a cable coming so I can use Datamaster. Anybody have any ideas whats going on?