98 civic ex automatic

parents have had this car for awhile, and about 4 months ago the ignition coil went out. finally got around to getting it fixed (she sent it to a shop that supposedly ran a diagnostics check and was supposed to fix everything). well she got charged 370 bucks to fix it. insane. but the problem is, the car runs like ass. the tranny has always shifted like shit, but the 1-2 shift is hard like slamming gears in a manual. thats doesnt really bother me, however the tach jumps around all through the rpm range, mainly in second gear, and the car jerks around, like its losing power then gaining it, then losing then gaining. pissing me off. that and the gas mileage has dropped from the usual 260miles per tank to like 175miles to a tank. anyone got a clue?