Car running pretty well with one caveat, should be easy for the gurus Options

[drewvw]

I have my stock 1.7 running pretty well lately with all the work I've put into it. Only one obstacle remains:

When the outside temperature is warm, the car runs well and is very smooth. But when the temp drops below 50 the car stumbles a bunch unless I really get on the throttle. To me, it feels like it runs too lean when its cold.

I've done the archival research, not many threads that address the outside temp as opposed to the engine temp.

What do you think? bad temperature sensor? vacuum leak amplified by cold weather?

[Dr Evil]

Some factors to consider for temperature dependent mixture:

AAR, is it working or lettingin too much air/not cclosing
Cold start valve, is it hoked up (although it is supposed to only work at like 35 degrees)

Not coming up woth anything else off the top of my head. But basically, if it is lean then something temperature dependant is leaning out the mixture.

Is this only on warm up or after it is already warmed up as well?