it's a 2000 kenworth. Checked the oil and it's pretty gross after only 2 months. any ideas what the problem could be? It seems to drive okay under 1700 and once it hits that mark it starts to bog down and the oil pressure shows low??

Could be that it's computer nueters the engine power, retards it, after you hit 1700 rpms. It's a way of governing the trucks that many companies use. Won't allow it to rev past a certain rpm in any gear.

As for the low oil pressure, could be a bad sensor or the wrong weight of oil in the engine or again, part of the above mentioned.

Has the engine had any rebuilds? Might need a serious overhaul or a whole new power plant.

change the oil and oil filters
if filter is clogged up some,and the oil pressure is lower than it should be,then when the motor runs high rpm`s,it calls for more oil but the sensors see it as low oil pressure and warning light(s) come on
mine was the check engine light

I changed the filter and it fixed all that