88 Civic stalling problem

1988 Civic began stalling during deceleration and downshifting right after I changed the radiator and cleaned/oiled the air filter. I over-oiled the air filter which caused the engine to idle extremely high, so I turned down the idle. Have since readjusted idle back up and car continues to stall. Car ran fine before I did the radiator and air filter.

I listened for vacuum leaks and didn't hear any, but I've never actually heard a vacuum leak before so I don't know what they sound like. Are they loud or quiet? A friend said change the fuel filter and put injector cleaner in the gas.

Can anyone help me out with suggestions?

Hey, I figured it out. It was the brake booster. Problem solved.