lost communication with PCM
 

lost communication with PCMhello everyone im new to this forum an i was hoping i could get some help i recently bought a 99 pontiac firebird for a 1000 changed the battery drove it for a while then parked it till i got parts for it eventually i got plugs oil general tune up things and new rear end performed the tune up and changed the rear end out drove it for a while and parked it so i could get it legal sat for a few days went out to start it and it wouldnt start the only code it was throwing wat for the throttle body so i found one changed it out tried starting it nothing scanned it same code but also had a code for the app module (one on the throttle pedal) so i changed them out code for the throttle body went away but not for the module on the throttle so before i change the module i scan it and it comes back lost communication with pcm so i change out the module on the throttle scan it and the code for it is gone now but the only code that is left is the communication with the pcm is there any way to fic this with out having to buy a plug and play one programmed to my vin and if there isnt a way to fix it is there an advantage to getting a plug and play pcm for my car they are like 140

before i bought the car
car had 120xxx miles on it
sat for around 2 to 3 years original owner said he would start it every now and then
have all documents of maintenance with nothing showing that any major work had to be done besides tune ups and alighnments engine flushes ect