I am having similar if not exact same problems. Engine cuts out between 3-4000 RPMs, not on WOT just in acceleration. All speeds, all gears. I pulled out a code 1221 for O2 sensor, changed it, but still have the problem. The old o2 sensor actually was pretty white, so I am in a lean condition. I am thinking vacuum leak or fuel pump/filter. Anyone have any other ideas? Looks like this is a common problem with many different solutions. Hopefully we can all get it solved! Thanks!