I know the flutter feeling and currently have it myself. It's driving me nuts. But in all other respects the engine runs fine. Beats the shirt out of me.

Recheck compression with another tester. I'll bet yours reads low.

If the compression is even on the cylinders (and it is), then that's not causing the flutter.

Next step is checking fuel delivery to each injector.

Thanks. I actually did try two different gauges - one old Snap On and one new one from my local parts store (O'Reilly's). They were practically identical.

The fuel output of each injector has been tested (and replaced with new, and tested again). Really, EVERYTHING* has been tested and/or replaced. By me AND my very good mechanic. The only thing left really is the P&Cs.

If you ware saying you have the same flutter, maybe I do need to give up - or try the non-Cal gas to see if it could be contributing.

* I should say in desperation, I asked about the gas tank venting and gas lines, which have not been tested, and are original. But everyone I've asked said it can't do this.

FWIW, my guru tells me that my motor runs best at around 3% CO. Find someone with a CO Tester and adjust accordingly. This is richer than factory and may require adjustment to pass emissions.