Cummins/Case 6T Engine Checks

I have a 850G with the 12v Cummins (3500hrs on meter) and have a few questions. The last few times I've ran the dozer the engine will stumble like it's running out of fuel. This only happens after pushing heavy brush and letting of the accelerator to go into reverse and it might only happen 2-3 times during a 6-8 hour day. The fuel filters only have 100 hours on them and the tank looks clean so I'm kinda leaning towards a fuel pressure issue. I know the pressure should be 5-7 psi under full load but I'm not sure where to check it. Also wondering if the Primer Pump is the fuel pump for these engines or only used to bleed the air out of system. I have read through the service manual but there is not anything I can find on checking fuel pressure. Also wondering if anyone knows how to do a quick blowby test to check engine wear, other than the manometer test method. Thanks

Cummins/Case 6T Engine Checks