My 1995 Toyota corolla trew a dtc 25 code and it pings when under acceleration

Sounds like it may be out of time which would be a timing belt replacement. It is a interference motor so if its too far out it will bend the valves in the head. The o2 sensor will give code 25, may be time for a new one

Thank you for the reply. I've already had a look at the timing belt. It's pristine. ..looks like new and it's tight. It doesn't have a miss or run poorly, so I'm pretty sure the belt and its position is correct. Overhauled the fuel system, replaced the idle air control motor, tps, MAP sensor, cleaned the throttle body inside and out, overhauled the ignition system, replaced the injectors, thermostat, radiator, accessory belts, exhaust manifold and gaskets, checked my grounds, anddid a smoke and water test for vaccuum leaks. I'm at a loss.

Then maybe cam position sensor but the o2 is the one that gives the code 25