I've had my 03 coupe 6mt for about 3 years now, and the only problem I ever had were some bad 0 2 sensors, I would change the air filters, oil and filter etc, even the spark plugs.
About a year ago my car started to run real poor, it idled high, it would stall, and consume so much gas.
I've tried everything, I've changed the spark plugs, I'd clean the maf sensor, throttle position sensor and it would not fix the issue, but it would get alil better when I clean the intake system. I believe this issue started after I changed the o 2 sensors a year ago, could it be?? In cold starts, it would surge almost like there is too much gas in the motor on start up, so the car would choke up alittle and it has a random misfire too... Last codes I got was, idle was too high, and another one that said, running rich I believe, I've tried it all, have you had this problem? I've done the relearn process, all of them and nothing seems to work. Help please!! I also noticed my air suction isn't as loud as it used to be:/

 

Ever think of following the troubleshooting steps in the FSM?

Telcoman

 

Bad fuel? kink in the fuel line or maybe a bad injector?
Possible vacuum leak maybe around the plenum after the spark plug change.

 

dude you remind me of the state farm commercial when aaron rodgers asks the fan if that is all he says.

but on topic. it sounds like an air leak. make sure all your connections are tight and there are no holes or disconnected hoses.