Fuel pressure problem
 

I just replaced the fuel pump with a factory pump as well as the pressure reg. I shimmed the reg to 70 psi. My problem is I'm getting eratic(sp?) fuel pressure.Sometimes a steady 70 psi then it will drop to 60 and jump all around.Shut it off,wait a while,back to steady 70?Acts like a bad pump.I'm also running oil/diesel at a 50/50 mix.I'm taking my reading pass the check valve in the filter bowl by the injector lines.Do these pumps not like the 50/50 mix? A friend in Al. has been running it much longer than I with no problems.Any ideas? Thanks,Bob