Hey guys, Im a new third-gen owner. I recently acquired my dads 91 Z28 L98/700r4. It has 81,000 miles and runs great. I recently did a tune-up on it(bosch platinum plugs, Standard wires, Cap and rotor, and coil). The problem with it is, after the engine warms up, it starts cutting out, usually under a load. If you drive it easy, its fine. I was thinking maybe fuel delivery, but wouldnt it do it All the time, not just when its at operating temp??? I also replaced the TPS sensor. I did the coolant bypass mod on it recently also, could that have anything to do with it??? I also have been told it could be vacuum or the O2 sensor. Please help, Im running out of possibilities. Thanks in advance....

Mike Estep

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1991 Z28 5.7tpi stock except for 3in flowmaster exhaust with 2 high flow cats, and the tb coolant bypass.

 

Vacuum leaks and timing could both cause your problem. Checking these would at least be a good place to start.

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'86 IROC-Z, 305 LG-4, T-5, T-Tops, 50k Original Miles, K&N Air Filter, Jet chip, KYB Shocks/Struts, Centerforce Dual Friction, B&M Ripper Shifter, Hooker Super Comp Shorties and Y-pipe, Catco Converter, Flowmaster 80 series, 3 inch custom exhaust

 

Check your fuel pressure while the engine is running. Your problem CAN be due to a faulty fuel pump.

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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps, MacEwen white-face guages
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi