Idles fine. Give it gas it backfires misses stumbles

It has 158,000 miles on it. Was running great until got gas with water in it. Or at least what I was told

So, if I understand correctly, you have never actually had the car running well enough to drive on the road? Take s fuel sample to confirm or deny the 'water in fuel' idea. Then it's back to basics, air- fuel -spark. Test and or visually inspect to prove correct fuel PRESSURE, correct valve timing (chain jumped?), air(MAP/MAF)-broken intake hose ,etc.

Been driving it for about 3 months. Was running great until I got gas one day then started acting up. Dad said he got gas there also and had water in gas

Take fuel sample and if that checks out okay , check timing chain. Map sensor READING or vacuum gauge could also be used to watch.