Ecu uses ect sensor to determine cold start enrichment. When it's bad, it usually fails in such a way that the ecu doesn't know the engine is cold, so no cold start enrichment. As a consequence, the starting mixture is too lean to fire off cold. This usually starts showing up when the weather starts to turn colder, like lately...

In a few cases, I've seen the ect fail so the engine thinks it's cold when it's not, and you run very rich...

Not responsible for advice not taken...