97 cavalier auto 2.2 problems......

okay 97 auto 2.2 80,000 miles new plugs/wires/pcv valve/air filter/oil filter/ fuel filter/ because a month ago # 4 cylinder injector was stuck open. engine became hydro lock with fuel. I removed plugs cycled engine replaced injector, cleaned spark plugs regaped. but now was getting a misfire on the replaced injector (either air/fuel/spark) although the wire that connects to the injector was previously coverd in gas and could have a problem. used a stethascope and compard to the other injectors the new one was .... clicking? louder i could here it loudest at #4 cylinder and barley at #1 .... same time i checked my oil with the car on and there was alot of air coming out of the oil fill cap. not smoke
and it dosnt smell like exhaust fuems like from the tail pipe. Just air in sinc with the engine pupupupupupu.. checked the pcv valve.. it was fine the hose was a little old but i didnt feel any air. im not loosing any oil
no leaks under the car and it runs good. whats with the air in the oil fill cap? NEED al the help i can get. James