Sounds like a warm-up enrichment issue, especially if it runs fine when it's at operating temp. If you're running it in 4th @ 35MPH, it's no wonder it takes a while to warm up. RPM's create heat, not distance. Try downshifting so it'll warm up quicker.

As far is taking longer to warm up the colder it is outside...that's pretty much a given.

Do you have the FSM for that vehicle? Seems cheaper to buy that, learn exactly how the system works and then replace the correct part than to throw multiple parts at it on the off chance you may accidentally fix it.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.