Many years ago I put another engine in a rover 75 after it melted along with some of the wiring loom, I stripped all the loom back to repair it and on refittment I had mis-connected two 3 pin multi plugs on the wrong place.

Think I'd put the cmp sensor plug on the throttle pot and the tps on the cmp as I'm sure they are the same plug.

Although this wasn't the actual cause of the problem I had with it not running and difficult to start (shorted internally power steering pressure switch) it certainly didn't help but unfortunately I don't remember what codes I had logged.

Was probably 8 years ago now though. Just thought I'd post this just incase as I know you had the wiring loom off.