I had same problem with C&L as soon as heads and cam went in. Ok with intake, TB and 1.7 rockers though. Changed sampling tubes each time I changed injectors, kept getting check engine lights also.
I have Pro-M 75 in car now, have used 77 also, but couldn't pass visual inspection on smog test here in Calif.
I am very happy with the Pro-M, only hassle is having to ship it to recalibrate it if you change injector size later on.
Have heard lots of people very happy with the C&L, mine is in my friends '88 GT w/ 4.10 gears, TB headers and it runs great.