grand am stumbles,backfires

Ok I have a 94 grand am with 2.3 quad 4 sohc it was running great until I washed the engine and evreything under the hood.It runs fine cold for about 2 min. but when the engine is warmed up about 15 min. later, : it starts to stumble and back fire and I also noticed that at the end of the cat. it gets red hot?

This forum site sucks,you pepole don't know shit I already found the problem

This forum site sucks,you pepole don't know shit I already found the problem
well dont put your message on her people have a life besides returning everybody message people work you no and it probably was the cat stop up and you the dumb one certain things under the hood you suppose to cover up and dont wet them.

Sorry that was my stupid little sister who wrote that,anyway I found that coil pack housing was bad runs great now,thaks for the tip though.