The I30 had to be towed to our garage. It would start every time, but the idle would slowly drop then eventually die. Hitting the gas would cause it to die instantly. Fuel pump, fuel filter and TPS are all brand new.I started it and played with the throttle enough to rev it up and let it run at high rpm for about 20 seconds. The car at least held idle after this but was running a little rough. While poking around I noticed a whistle like sound coming from the area around the back of the engine on the passenger side. I searched for the location of the sound with a stethoscope for some time but couldn't pinpoint it. Not sure if it has anything to do with this problem.The owner says he occasionally gets a CEL for the knock sensor, but it is random. It is not currently on.

Any ideas? It's like finding a needle in a haystack right now.

he doesnt get a CEL for the knock sensor.

check the evap line coming up to the purge volume control. check the air tube from the maf to the engine very closely for holes. If nothing is found there try wiggling the harness by the right hand strut tower see if it helps the car run better. if ok take a look at the ecm connector check for water stains from the evap over flowing from the lower heter vents.

also take a look at the PCV valve make sure it hasent poped out.