Thread: impala cat's ?

i got a 2000 impala 3800 and its running real ruf but i changed the plugs and wires and now it runs really good but when i come to stop it wants to die out. i was thinknig its maybe bad cat's so i was wondering if theres anyway to tell if thats what it is or not or if anyone has had problems like this before and if so how did they fix it? thanks

vac leak?

I take that back, a car with a vac leak doesnt run well.

Any codes?

yeah it was reading misfire on cylinder 3 but changed the plugs and it runs great and then it came back on a said cyliner 1 misfire but we cleared the code and it hasnt come back. i know the car does have a veryyyy bad valve cover gasket leak to. but when my trans ams cats got clogged it kinda did the same thing but the car eventually just stopped running and once i put new ones on it was like the car was brand new again.