El Brujo

Hi There, A few weeks ago my car started to run really rough all of the sudden (just after starting it up in a store parking lot). It chugged home, then died several times while trying to parallel park, dying when in reverse. I saw a tip on here that led me to opening the air intake with a slotted screwdriver. I actually did up to three counter-clockwise turns and it has helped. I can drive it forward and in reverse without it dying, however it is still running very rough. The engine is vibrating quite a bit, and it making a chug, chug, chug, chug sound. When I opened the air intake, I can now hear some suction sounds coming from down near the right front headlight. I believe this is the issue, because it would barely start for me before, and was dying while in reverse. One year ago I had the exhaust system fixed, ignition system and ignition coil tuned up, and the fuel system motorvacced. There is plenty of fuel in the tank, and the car has 155K miles on it. I would appreciate any advice as to what I should be looking for. I'm not familiar with fixing cars, but I'm not completely hopeless either. Does this sound like an easy / cheap fix? Any danger with opening up the air intake as much as I did? Thank you very much!