Ok so heres the story. When I first bought my car, about a week past and I got a P0430 Code, which turned out to be a bad bank 2 CAT. So I had that replaced for about 500$ under warranty.

Now, warrantys over, I have a 1 year warranty on the shop and their work / parts/ etc, and when I drive, sometimes My car "Lags." That is the best way to put it.

Dont know what causes it, because sometimes I accelerate hard, sometimes I dont, and after prolonged periods of doing either or, (I'd say about a hour of driving at most.) my car makes a "farting" noise when trying to accelerate from a stop or a very slow roll. I can tell its the exhaust. The car dosent pick up speed as quick as it did when it was first driven, and there is less throttle response, unless I push it about a little above halfway down, the car starts to pull again. Right when i hit 2k RPMS, the noise silents, and the car is "normal" again. The idle is very quiet and stable. Sometimes when it is hot outside, and I shut off my car for whatever reason and go to turn it back on within at least 15 mins, it is a very hard start. ( has happened about 4-5 times since I bought the car.) Is this the sympton of a bad Cat? A Clogged Pre Cat? I plan on getting a new exhaust soon, because my tail pipes are rusted, stained and old, but until I get it, I would like to know my issues. Also the car always stays at operating temp, never overheats. Not throwing a SES light either, but I havent checked for codes yet.

Havent taken it back to the shop or Nissan yet. Any input is appreciated.

BTW Sry for the long story. Trying to give as many details to help solve the problem.