I did something I've never done before, bought cheap diesel of a bloke down the street for my 7.3 IDI, almost immediately the truck started running rough, misfiring, hardly any power, top speed 15mph, drained the tank and lines, fitted new filter, filled up with fresh fuel but still running the same

 

There must be some of that bad fuel left in the lines, I guess you could try leaving the truck run for a while to see if it burns the rest of it.

 

So you didn't buy it from a station. Just a random dude?

It could have unlead in it.

 

nope drained it dry, pumped fresh fuel through the lines, i think it's damaged my IP

 

I bought it off a so called friend, the price of fuel here in the UK is ridiculous so it's very tempting