I have a modified LS1 with GM hot cam, 243 heads, FAST intake, headers and 90MM drive by wire throttle body.

Where should I start looking for these issues?

1. The RPMs are high on hot starts, but after a few seconds the RPMs come down to 900 RPMs.

2. When you accelerate heavily, the RPMs will flurry when engine comes down to idle.

3. Occasional P0507 code (idle control system has an excessively high RPM)