Went to a wedding this weekend, and every time I accelerate, it shakes badly and feels like it has no power. Isn't any worse when I'm going uphill. About the same. Can't exactly go over 75 without it shaking pretty badly. When I tested it around town the today, I accelerated pretty quickly at the stop sign to find out what's going on.. and yep.. didn't have much power until I was in 2nd gear. Didn't shake much. Seems like it gets worse when I drive it for a long period of time. Can't figure it out. When tires were put on.. they didn't balance and rotate. But I don't know if that's my problem, because it was there before I had that work done.
Advice? Steps on what to look at first and what to replace? Work my way up from the easiest to the more expensive/harder stuff?