i have this same problem.. i've got an 11lb flywheel, but sometimes when the compressor kicks on it sounds SUPER LOUD, and Idle Fluctuates 3-500 rpms up and down for about 3 seconds.
Something i've always wondered, can you Wire the FICD valve wrong?? in my b13 there was a blue wire and a black, if i'm not mistaken.. on the VE FICD plug/pigtail there was one matching color, which was the blue i think. I just spliced the matching, 1 color, plug and spliced the other 2 odd color wires...??? Might have we made the mistake here???