2006 Buick LaCrosse - Loses power

car runs fine sometimes other times car acts like it is not getting any gas and loses power on acceleration

Well, since you did not ask a question, my crystal ball will leave you with this…

Buick Recall 14299: Ignition Switch May Turn Off — 2006 LaCrosse | CarComplaints.com

No acceleration or RPM increase while pressing gas pedal … (yourmechanic.com)

also a possible faulty fuel pump.

A clogged cat could cause that symptom too. Sometimes a damaged cat will sporadically act like it isn’t clogged b/c the substrate shifts enough (for example as a result of going over a bump) to allow the exhaust gasses to temporarily pass unobstructed.

I’ve had that problem due to a clogged fuel injection system too.