abs light on and slow acceleration with bumping

Better set and appointment with AAmco and have them double check the transmission and related components. A diagnosis will reveal the issue at hand, and it may not be related to the work they've done.

On a Chrysler 300 if you have an ABS trouble code then it can cause transmission issues. Yes I agree to take it back to Aamco and let the technician scan the ABS system and that could possibly fix your transmission problems.