The engine controls have a rev limiter that kicks in between 3500 and 4000 rpm in N or P. Otherwise, in gear, the rev limiter is 6300.
Nothing to do with CKP's or CMP - those stall occur at low speeds, not 3600 rpm in P.
The idle speed stall is probably a filthy throttlebody or IAC solenoid/valve - go down to Discussions, Technical Tips and find one of several threads concerning throttlebody cleaning.
use 70cougar's link to learn how to get your Diagnostic trouble Codes from the car's built in scanner/reader, and go back to the post to open the link to the code definitions. Write them all down, whether each is Current or History, and come back here.
The oil consumption. First DO NOT keep the oil at the top mark on the dipstick. Keep it here on the dipstick:
<---- ADD XXXXXXXXXXXX OPERATING RANGE ---------------------------O
Second, go up to the black bar ^^^ and read the entire Cadillac Technical Archive, particularly the article "Occasional full throttle operation is good for your engine". Northstars driven quietly, mostly city, tend to consume oil.
