I have a 91 Acura that won't shift into D4 the car shifted fine I had a blown head gasket I had the motor and tranny changed. Then the tranny would not shift into D4. I then had the shift solenoids changed still didn't work. I had the old tranny that I knew worked installed back into the car now the tranny still will not shift into D4.

 

have you checked the shifer linkage? its under the console.