Fuel supply problem is possible, but I was thinking more about the fuel/air mix. If it's running too lean, there might be evidence of this on the tips.

Wonder if your ECM is mis-reading the new o2 or mixed signals from the MAF.

Have your experienced any predetenation? Any slight pings or knocks?

As you mentioned, it would worth the effort to run some quality injector cleaner through the tank.

Travis

"I can make it up the hill in 2wd, Honest! I'll just go FASTER!"