Car Probs on 89 Accord LX

Hey guys, i have a few probs with my 89 Accord LX. First, its not getting very good mileage, its getting about the same gas mileage as my 88 Thunder Bird w/ a V6, and my Accord is a 4cyl. Also, it never really had any power, but it seems to have less power now, especially when trying to accelerate. Also, sometimes when i turn the car off, it starts to rumble, as if having a hard time shutting off. I was wondering if this has anything to do with my carbeuateur.

P.S.- i bought some hub caps, and they dont fit on my car, and they are the correct size (13).

Also, i was if anyone know of a good paint job place in the Los Angeles, Riverside area, cause i hate the color of my car. It would be nice if it was under $1,000.