Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Sounds like the fuel rail is bad and returning too much fuel causing low pressure at high rpms.
Here's the test for it:
1. Measure return flow from the FPR 2 port on the front LH fuel rail, (return hose removed and plugged). Place a hose on the port on the fuel rail, and place the other end into a container (fuel can).
2. Start and run the engine. With engine at operating temperature, hold RPM at 1800 RPM, measure return flow from the FPR 2 for 15 seconds.
3. If more than 10 ml, replace the fuel rail assembly on the LH side.