2001 Chevrolet Malibu Surging

2001 Chevy Malibu has been surging for the past 2 years, just going up hills. I reach about 19000 rpm's and then it surges to 23000, up and down, up and down, the only way I have gotten around it, is putting the DRIVE into 3rd gear. In 3rd gear the rpm's are at 25000 and the surging stops, but that's only on the freeway. About a year ago it started surging after making a right turn, going over speed bumps, going over dips, going up hills, when the car stops suddenly. The transmission has been checked, I had just replaced the catalytic converter around the same time the car started surging. I took off the MAF and the car stopped surging but it rode rough. I replaced the MAF and the car still surges. And now it even starts to surge when I'm just driving straight down the road and I excelerate. I put the OBD2 machine on it but it does not have any codes(DTC'S) on it. Please help, I don't know what to do.