ok let's see if I can explain this properly, 2007 focus SE 2.0L, automatic transmission, 170,000 mi., tranny slips during gear shift at around 20mph, but only with a cold engine and very light acceleration, if my foots into it, it shifts fine.
This will only happen once and only with a cold engine, after the first slip it shifts fine, it won't slip again until the engine is cold. It's been doing this the last 15,000 miles or so. Iv'e learned to deal with it but was wanting to get some advice.

Thanks, Ray

 

Anytime any transmission slips it generates heat and heat is a transmission's worst enemy.

Abnormal wear is taking place when it slips and it does add up.
When was the trans last serviced? Might be a simple fix..