Sudden loss of power at speed
I have a 2000 SSEI with 185K on it and in good shape.
Today I was driving down the highway for a good 70 miles with the cruise set to 75. Started to pull a slight grade and as throttle pulled in, engine began to stumble pretty badly. Disabled the cruise and backed off accelerator problem eased. Manually back in on accelerator and stumbling began again and then began to knock. I backed off and babied it for a few miles to ensure no smoke, leaks or temperature rise. Began to pull another slight grade and noticed that boost gauge rose abnormally even with slight increase in throttle. As boost gauge exceeded 7psi into the yellow, the engine would stumble very badly and begin to knock.
Stopped at off ramp and shut engine down and restart to see if engine computer glitch. Same problem existed.
Well, headed back home and babied it all the way. As long as boost gauge did not go positive car would run fine. Got back home let car cool to see if any obvious problem. None found. Took back out for 40 Mile hwy drive and problem did not reappear.