My truck's engine could not idle in cold, winter weather. This problem began two winters ago. I took it to 2 different mechanics & replaced/serviced multiple components myself----which all FAILED.
Then, I took it to Taylor Auto Care. Diagnosis: bad manifold-intake-gaskets were allowing too much air into the engine when cold; In warm, summer conditions this problem was not happening b/c the gaskets(when warm enough) expand sufficiently to do their job: seal up air gaps.
more