1997 960 codes

[wholesale boxes]

car has 4 codes, 172 rich bank 1, 300 multi misfire, 301 #1 misfire, and 302 #2 misfire. so far i have changed the coils wit 2 known good ones. compression test ( all aprox 225 ) checked wiring to coils, changed 1 & 2 injectiors with 5 & 6 . cleared codes. they all came back but the 172 but if i run it longer i am sure that would come back also. i was thinking of the ignition amplifires ???. thanks for any help. chuck