Won't run cold
I have a '96 F-350 4x4 with 370K miles and it will not run properly when the engine is cold.
After initial starting, it will idle fine. However, if I do not let it warm up for about 10 minutes or so (depending on the outside temp), it will start to bog down and lose power from second gear on - the colder the engine, the earlier the gear it will start to bog.
It starts out fine, but generally will suddenly start slowing down in speed somewhere above 30 mph, and the engine RPMs will slow down. If I apply more throttle, it will bog, puff white smoke from the exhaust, lose speed and RPMs faster, and likely stop running. If it does not stop running and I pull over, it runs as though only firing on some of the cylinders. If it dies, it is very difficult to start and will run very rough until it warms up.