Isx skipping under heavy oil load and small oil leak

[Luckyjayb]

Good morning guru’s. I have a 06’ international 9900i eagle with a 13 speed manual, 40k rears, and 3.55 gears with a 565 Cummins isx with 1,003,325 miles on it. I just replaced the front main seal and that stopped my major oil leak but now it looks like it’s the oil pan gasket. Everything on the front cover shows no indications of leaks coming from there. Any ideas on that? Also I usually pull 77k-80k gross and when pulling a steep grade, when my rpms drop to around 1450, while in 13th gear, I get a quick skip and a good puff of white smoke out of my stacks. The motor hasn’t been tuned and still has the egr. It is maintained meticulously. It’s a cm870 if I recall correctly.