Check engine light on 1990 Ford Mustang GT

when on the interstate my check engine light comes on and goes off every once in a while. I just had motor rebuilt new tranny new clutch new O2 sensors I am lost. The only thing I haven't replaced is the fuel pump and fuel filter.

1 answer 2 comments
if you are changing altitude , the o2 sensors could be reacting to thinner air. it was not uncommon for obd 1 systems to re act like this.
have it double checked at a shop to confirm.

Roy
The altitude isn't changing. It started after heavy rain but on the coast here there is no change in altitude
ok, then you need a shop to pull the code with an obd 1 tester to get the code and diag it to determine the issue. if you give me the code, i can guide you from there.

Roy