Just got my first car its a 2000 GT 5 speed with 110k miles. The previous owner had bought the car knowing there was a loud knocking thinking it needed new rod bearings. Other than that the car had run perfect. But the owner ended up just letting it sit outside for about 2-3 years without fixing the problem. I've always wanted one of these cars and he ended up giving me a killer deal on it so i had to buy it. When it comes into my possession, the car now has a check engine light and a very bad idling problem where it skips and every few seconds it dips down to 300-400 rpm. And of course it still has this knocking sound when it revs over 2000 rpm. Anyone have any idea what could be causing these problems. I've already checked the coil packs and spark plugs they are all fine. Added new gas to the car thinking it had something to do with bad fuel since it was sitting for so long but that also wasn't the issue. Don't know much about these cars so if anyone could help me that'd be great. Keep in mind the car has been sitting for 2-3 years. If worst comes to worst might just swap the motor.