Why does your Geo Metro jump and backfire and only go 35 miles an hour?

i would check cylinder compression, and definitely the timing. if you have good compression and timing is good, i have found that a bad or slipped timimgbelt or even, I've found the crank gear keyway bent or broken allowing the gear to move just enough to go out of timing. also check your distribitor cap and rotor. all of these things can cause your prob..