Can't advise on the CPS readings - 492 is pretty close to 540 but, obviously, 516 is closer.
What diagnotics have you done? Did you run the stomp test and get a CPS code? Have you checked the fuel system to make sure it's pressurizing? The fuel pump relay is a common failure on these cars.
My advice, stomp test the car and get the codes. Verify you have fuel. Then worry about a 40 ohm variance on a CPS.
Jeff
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy