Getting your
oil analyzed will tell you for certain if you are loosing a cam. The other down and dirty is to measure each valves lift at the valve. If the cam is going away you will see the loss magnified by the rocker ratio of 1:7 so it shows up quickly.
Remove the V covers and bar (turn crank shaft) through the firing order while measuring each lift at the valve. Use the end of a dial caliper (the rod that extends out the end) when the caliper is opened and measure between the head surface of the spring pocket and the spring retainer. Compare all intakes lifts and all E. results to each other. If all the intakes are within say 0.010" you are good to go and same for E.side