Voltage drop

[fillpot]

Guy's got a LS2 in a 69 Camaro and having a little problem and thought I would ask a quick question, the car will crank and run fine for a couple of minutes then it just starts running like crap, want idle, missing etc, I'm going to check some stuff out on it tonight voltage at pump and some other things but was wondering if I may be having a voltage drop, and I guess my main question is do ya'll use a relay on the power wire going to the pcm, going to my tuner in a few days to for a retune after a cam swap but was just looking for some input before hand. THANKS!