hesitation and rough shifting problem

I just had the heads on my 95 Grand Am SE (3.1) redone and now I have a delay when the car shifts from 1st to second. I also have noticed a loss of power when accelerating. In addition, as I am driving down the road steadily going about 50, the car doesn't feel smooth but instead feels like it is studdering or hesitating. I know the mechanic said he did a valve job while he was doing the head. Is there any chance this could be a result of a loose vacuum hose or bad timing? The car didn't have any of these problems before it went into the garage. Any help or suggestions would be appreciated. I would like to have some idea of what it could be before I deal with my mechanic again. Thanks

Could easily be a vacuum line, but I doubt it is the timing as the timing chain would not have to be removed to do the work you had done.