New to site and fairly new to Mack trucks. The problem is with 2002 to 2006 ASET/AMI 300 Mack engines. They have been oil sampling But not doing anything to correct problems. We are running five of these trucks and they all have Mack tm309m transmissions. Changing oil every 8000 miles, but the oil is very high in soot. When driving these every gear shift will lug the motor. Probably a mix of the motor being weak and the junk tranny. As far as I can tell we need more air intake and more power. The problem is we need to do this right and one time because of budget restraints. Everyone that I ask about a good economical fix has no answers. There are plenty of people who can make Cat, Cummins, and Detroit wake up, but no luck getting answers about Mack. Any proven ideas would be helpful. By the way I'm not a motor guy, just a parts changer that understands trucks.