***at my wits end***

[00sd250]

2000 250 Superduty 7.3
This is what I'm up against...
Truck started having a "skip" with a very soft knock on the passenger side.
That "skip" turned into a knock and I did check the injectors...#3 was the only one that didn't make a difference....so I replaced it. While I was taking it out at idle it begin to blue smoke and act sluggish. Under pressure it cleared, but still with a "skip". Decided to go ahead and replace all injectors...after all it has 250,000 on it.
Still has a skip and knock...compression is good on all 8...gotta get this running
Any help would be appreciated