After the initial install, you should not be getting an codes as long as you adjusting the tune to take into account the new cams.
When it was running ok, did it act ok at low to middle rpm's and then act up at higher rpm's?
The VCT doesn't kick in until higher rpm's, so any VCT issues may have been overlooked. But now it sounds like it's got some VCT issues. Did you change the weight of your oil?
Something has probably been wrong since the initial install and now it's affected something else.
chevy runs deep, Don't step in chevy!
67 Coupe 289 - TCI C4 w/2k stall; Holley 4150 570cfm; Performer intake; mild cam; Pertronix HEI; 302 heads; Roller Tips; Hedman Tri-Y headers; H-pipe w/Flowmaster 40's; 9 in posi 3.50; 205/50-17F; 225/50-17R.