[GunMetalGrey]

Intermittently my car will almost act like cruise control is still on for about 3 to 5 seconds after downshifting before the car starts to slow down, essentially the car will start to slow down more than it just was immediately after downshifting even though the engine is at a lower rpm than it just was immediately after the down shift took place. It’s very intermittent.

The boost bypass valve was suggested as a possible culprit and indeed it was disconnected and not working but after repairing it the issue is still there

Any thoughts?

[Anslkyn]

I bet the problem is Throttle Position Sensor - The TPS tells the ECM how much you're pressing the gas pedal. If it's faulty, it might send wrong signals and cause a delay in throttle response after downshifting. And this could make your car maintain speed for a few seconds before slowing down.