'93 DOHC Backfiring problem

['90RPS13]

Looking at buying a new S13. Here is the problem with it. It idles fine. He parked it one night, came out the next morning and it wouldnt crank over. Got it to crank but when given gas, it backfires and SLOWLY revs to 5-6krpms. Sounds like timing eh? Possible to jump a tooth?

EM12487 (12:09:52 AM): like if u hit this gas, it wants to hesitate like
EM12487 (12:10:18 AM): but the day i woke up to drive it to work
EM12487 (12:10:31 AM): you could crank and crank and crank the motor, and it would never start
EM12487 (12:10:39 AM): then i went out like a month ago and it crank up..
EM12487 (12:10:48 AM): but ran poorly
EM12487 (12:11:31 AM): like when i got it running i tried to move it around, and it backfired like crazy
NinetySilvia (12:14:59 AM): so it will rev to 5-6000rpm but slow correct
EM12487 (12:15:14 AM): yup

Nib bit of our convo. Any help would be great.