1991 Nissan Maxima Major clicking and popping from engine.

I have a 1991 Nissan Maxima. The engine has been skipping for quite a while so I decided to change the spark plugs. I did notice quite a lot of dirt on the plugs before taking them out. Cylinder 2 had the most dirt on the plug so after getting the plug out, I took a blow gun to blow some of the dirt out ( a mistake I believe.). I put the plugs in and cranked the car only to hear it sounds like a diesel. I then took the plugs back out and noticed cylinder 1 had some oil inside of it and saw some oily residue from the exhaust. I put the old plugs back into the motor and still got the same thing. Does anyone have any idea what could have possibly happened here or any ideas and how to fix it? Please e-mail me at wildmandan1985@yahoo. Com, Thanks!