so i fired up my rebuilt 355ci engine with GM847. it started right at the turn of the key,,,everything looked good (oil pressure,temprature,and no SES light) except for the RPM, it keeps fluctuating between 500-900. i know its a big cam but RPM should be a bit stable if everything works fine even with a big cam like the GM847. i drove the car for few miles arond the block and when i pull my foot off the pedal RPM drops very low that the engine even went off on me couple of times
i know my fuel pump is not at its best, but i dont think that FP could cause this.
could my RRs be causing this? ...what do u guys think ?

other mods:
-ported stock heads
-3500stall
-LTs + TDs
-CAI
-58mm TB

ohh yes and my spark plugs are gapped at .045

 

With that big of a cam, you are going to need a good dyno tune. No way around it.