Put a scan tool on it and watch the O2 readings , I believe I mentioned doing this in an earlier post .

I also questioned the validity of the "90 #/hr" injectors you installed , were these from a reputable source such as Mr. Injector , or parts store specials ?

You need hard data to find the problem , scan tool data , at this point I am lost , both here and on Chevytalk.

TOM