Rov213

My c5 corvette sometimes surges rpm in idle. It surges in between 500-700 rpm then after a while it would maintain rpm at 650 and wouldnt surge anymore. Also after revving it high it would seem like it would stall. Rpm will drop to 400 then it would catch itself and surge up and down from about 400-700 like 3-4 times then it would stay back at its normal idle. This only happens when the car is in park or neutral and i rev it high. Never happens while i am driving the car and shifting or in traffic. It currently has the p0103 code when i run the codes. Not sure if the high MAF is whats costing it. Any ideas on what i should do? It is supercharged and tuned with a full exhaust. Recently ive installed dual valve springs, ngk spark plugs, a new battery, new pcv hose.