2002 Subaru Impreza TOO MUCH OIL!!!!!!!!!!!!!

Hi, I recently double filled my Impreza during an oil change. I drove it a few miles and it was running terribly. Once I realized what I had done, I drained the excess oil, and did and intake cleaning at my local garage. It runs terribly at low RPM's. It just falls on it's face at anything under 1,500 RPM. I have replaced the Cats, The O2 sensors and the MAP Sensor and it has had no effect. I would very much appreciate any input on this matter. It runs great once I'm off Idle, but if I slow down for a 90 degree turn, it almost dies, and it takes forever to get the speed and RPM's up. Please help. I have performed a compression test on all 4 cylinders and did a head leakdown test on both heads, everything there checks out good.