1994 grand marquis trans problem and motor ?
hi im new to this site i have a 1994 grand marquis i bought a couple months ago. Ive been having problem with the trans when i put it in to reverse it move slowly. one of my friends told me it could be the car may have set up a while and need the fluid changed. but i another friend told me the trans maybe bad and if i change it may get worse im new to trans so im looking for insight any help is welcome. also i wanted to know if theres any header or just bolt on upgrades for the 4.6 L im not sure of the exact year the motor came from.its not original. i was told the motor was from a police car.