I have a Sportage 2000 4WD. When cold the engine is missing. Get codes cyl 2, cyl 3, cyl 1, multi cylinder misfire. As temperature increases the engine smoothens out until it reaches running temperature then it is smooth as silk. I have replaced timing belt, exhaust manifold because it was cracked, oxygen sensor on manifold, coolant temperature sensor, fuel filter, spark plugs coils and wires. Cleaned idle control valve and connector. Vacuum checks good while hot but bounces around while cold (maybe caused by misfire). Seems to be related to a temperture sensor. No problem while the engine is at temperature, idle or running.

have you checked the maf plug for corrosion? these buggers corrode real easy an it woul lead to the engine bogging down when cold and miss fires.

Yes, but I will check again and check for propoer signal. The checks on the sensor are done when the engine is warm so I thought that it only effects the fuel/air ratio control after it warms up.