HELP !! My 99 LX I-4 with 38,000 miles runs poorly & sounds like a "lawn mower" when cold. Two miles into the trip it starts to hesitate almost like suddenly applying the brakes but occurs while accelerating & this hesitation happens quickly two to four times in a row before it ceases. I also notice while waiting @ a traffic light that the tach will increase/decrease (can hear engine accelerate/decelerate) in idle mode. The "check engine" light has come on three times and goes out by itself. All these symptoms only occur when the temperatures are less than freezing outside. If above freezing, the car acts/sounds completely normal. Water in the gas is NOT the problem. The "check engine" code is P0172, possible idle air valve. Dealers suggest several repairs. The idle air valve, the fuel pressure regulator, or possible cannister vent shut valve. Before replacing all, has anyone else had similar problems and what was done to correct the symptoms? Thanks for your help.