This start happening after I had my oil changed. I also noticed a decrease in mileage.
Sometimes with car in Drive, feels like low gear. feels like dragging. on 1995 Dodge Stratus
change spark plugs and ignition cables or coils to performance grade(E3 plugs and accel coils or cables). change air filter to high air flow design(K&N). use fuel additive(stab-ethanol treatment) to clean fuel system periodically(third tank). this may cost a lot initially but with fuel prices these days will pay off in long run.
Might be good to have the trans scanned at a shop.