is this only under heavy throttle? under normal its fine? if its under heavy that is like i said earlier every detroit i ever drove had it.

 

My first guess would be an injector. I would take it to a shop and have them connect to the ecm. It should not cost much and they may be able to tell you what the codes mean. I think the last time I had someone connect to my ecm I paid them about $40. Before going to the shop, you could disconnect the battery cables, leave them off for a few minutes and see if the codes reset. Take it on a test drive and if the problem persists, then take it to have the ecm checked. If the engine is missing, you will burn more fuel. Any Detroit shop or garage that regularly works on Detroits should have the ability to check the ecm.

 

I'll see if the boss man will let me stop by the KW garage. Between the codes, the vibration, the crappy pulling power, the shifting messing up sometimes, the loss in fuel milage, it should be worth him spending some money to have it all checked out. I want this truck in top condition, so when he retires I can buy it cheap

 

You could use your bullgear to check the ride height.
I can always tell when mine are hanging too low.

You see a lot of slow old bent rim trucks on the farms up where I live,
hauling in harvest, vibrating so bad, their fenders and hood shake,
and some of them are dragging their bullgear.

 

Mine started vibrating last Friday. Wasn't the bull gear, it was the pinion gear. $2160 later(plus labor) we are ready to go again on Monday.