Volvo 850 Lambda Light flashes and Engine hesitates

Dear Group,

I have a Volvo 850 GLT Estate 2.5 20 valve, UK L registration c.1994. At times the dashboard Lambda Light flashes and the engine hesitates, sometimes just once, and at others many times in succession. This usually happens on a run once the engine has heated up and more at higher speeds, mainly on a very light throttle, much less with a heavy throttle, rarely under full deceleration and breaking.

I have the Haynes workshop manual, and I checked the diagnostic module sockets and fault codes:

Module A Socket 6:

3 - 2 - 4 Camshaft position sensor absent intermittently. 2 - 1 - 4 RPM (crankshaft) sensor signal absent intermittently

Module A Socket 2 (Jetronic):

1 - 3 - 1 Engine RPM signal from ignition system absent or faulty.

Will replacing the Camshaft and or RPM sensors cure the problem, please, or do you think the fault lies elsewhere? I would like to do the work myself if it is not too daunting.

God bless,

David