Powering off first decceleration on cold start

recently had rear ball bearings and ac decompressor replaced on my 2002 chevy tracker (92K miles). car will lose power at first time i let my foot of the accelerator on a cold start. when this happens, it also pulls slightly left. i have been told fuel filter needs to be replaced. it also had been puttering on the first acceleration, but that seems to be fixed. any guesses on the powering off?