I have a 99 Vette stepped long tube headers, full x pipe and bb prt catback, ported ls6 heads by LPE, ls6 intake manifold, blackwing intake, stock injectors and coils, btr na stage 1 cam 223/230 .610"/.573" 115+2. Tuner said its got to be base engine related. I performed a cylinder leak test on all cylinder all were about 7-10 percent no issues found leaking intake or exhaust or coolant. I have checked made sure cam was in time properly, headers dont seem to be hitting anywhere. The wideband though is not hooked up these logs, i will have to hook it back up for a log.