cat. plugged or missing?

i was on the way to the airport to pick up my daadn and when i was on the highway the car was jerking back once every second. then i got off the oil light was coming on when i slow down at a light and just wanted to die. i pulled off some place down a road and it sounded different in the exhaust which was like theri was a hole in it( a while ago the muffler fell off so the guy welded it back on) and didnt feel like it had a lot op power. i got those platnum 2 spark plugs in and the mechanic said that those will cause missfireing in the engine if they are not in a high performance engine but they ran fine since i put them in last Oct. It only seemed to jerk when i stepped on the gas and when i would tought the brake the oil light would come on. so then after stopping at that place for a sec and left the car was barelly getting any acceration i had to floor it almost then i got back to the light and turned near airport and sll of the suddon the car was fine. is it missfirering or in the cat clogged? wut else could cause this problem?

what brand plugs did you buy. if the are bosch then take them and trow them as far as you can. how many miles are on your cat

what brand plugs did you buy. if the are bosch then take them and trow them as far as you can. how many miles are on your cat
yeah it is the bosch but how come my car ran good with them for 3 months then. not sur i got 133 on the cat and sicne i dont have the whole history of the car all i can tell u is that the cat looks rusted. me and dad are going to repace plugs this weekend. GTPdad had said that the cat isnt plugged iff this is so can u suggest some other probles that might be causeing this one that will be easy to check.
im guessing it hat maybe about 20k on it for the cat.(just a guess, maybe its been on their the whole cars life)

what brand plugs did you buy. if the are bosch then take them and trow them as far as you can. how many miles are on your cat

what brand do u sugest i use?

i have a 2000 2.2 cavy thanks

bosh usually last around 15,000-30,000. I have ngk in my car but i don't have an opion on them yet. but the ac delco ones worked fine for my car for a lllloooonnnggg time lol