1995 cutlass shifting problem

Howdy, My 95 cutlass supreme has a new problem. It seems to shift too soon causing a jerking and bogging down. It also sputters when I'm on the interstate and step down on the accelerator. 25% of the time it simply runs great with no problems at all. It started doing this right after I had the rear break lines replaced. Could they have knocked something loose or something. The trans fluid looks and smells new. Any help is appreciated. Confession, I'm no mechanic.

This requires some diagnostics, low fuel pressure, clogged fuel filter, bad maf, many things can cause what you describe, no quick answer for this. Usually what was done on the brakes shouldn't affect performance unless a line was crushed or kinked during the process.