RPM 's Bounce

[Neighbor]

Got a 06 cm870 inframed and de-mandated from a member on here with only 40k on motor. My problem is when i push in on clutch or throw it nuetral to coast down hills my rpms bounce between 700 to 800 3x, every time. I can hear the engine doing this not only the cluster. At high idle its fine no problem. Last week i replaced all the metering and timing actuators, got a good deal on them. Injectors where replaced 4 months ago oem recons. I read from a previous post maybe to look at the turbo actuator arm even thou the turbo was replaced during the inframe oem. Im going to look at the tps sensor, and at that air controller the sends air to the turbo actuator. Any other suggestions would be appreciated. And already did cut out test on my lap top with insite, never no codes. I can tell you that pretty much all the sensors are probably old and never been replaced. Thanks in advance to any ideas.