I've got a beautiful 3.2 Gtv with a modified engine (cams, heads, compression, valves, con rods were all done) that develops around 305 bhp. My problem is the car starts easily and will idle like a sewing machine while warning up but once warm it sometimes idles like a v6 with the Maf disconnected. Not always though. It sounds as if it may be "hunting" with the revs cycling once per second from around 650rpm to around 950 and dropping again. It pulls very smoothly and is very responsive from idle. There are no fault codes at present. My question is what will cause the car to behave this way? Could it be throttle or Maf related, or would it be a cam timing issue? What makes me not want to suspect the cam timing is that the car idles perfectly most times and just sometimes acts up like this.