My OM603 started to pulse under acceleration. If I back off a little on the peddle it goes away, if I try to give it more fuel it pulses again, like it's starving for fuel.

I took the heat exchanger out of the loop, and ran the fuel line directly to the lift pump with no change.

I pinched off the return line no change.

Changed both front fuel filters. no change.

Have no issue with fuel coming from tank...

I'm guessing ordering a new lift pump would be next?