PLEASE HELP!!! 6.2 no power all smoke
 

I posted once in the 6.2 dept but cant get a response from anyone.1985 6.2 k10 Always started first crank never smoked a lick.I choppped off stock mufflers and added Thrush Turbos havent got the new pipe and welded back on yet so it just cuts off after mufflers.I ran some waste motor oil through and unlike my Mercedes this thang dont like it! I have been through a whole nother tank of straight Diesel from the pump and replaced fuel filter three times.It is getting slower and slower and smoking more and more.Finally today I had to park it and get a ride because I cant even hold 45mph on a flat road without passing gear and it smokes like a freight train.What do I do?!?!?!?!? My oil pressure fluctuates like crazy (20-pinned at 80) and very randomly as in not dependent on the throttle position .Im not new to a gutless beast diesel and the 0-60 in 6.83 minutes but I mean this thang has NO power.in order for me to get it up to 35 I pretty much have to floor it and redline the rpms and still it smokes so much blueish and black smoke that I cant even see the intersection in my rearview after crossing and still have trouble making it up to the 35mph speed limit with 45-50 as my absolute max speed.I was doing 23mpg 75mph smoke free highway cruisng two weeks ago now Im looking at 15mpg and cant even get to work I need help ASAP!!!

update
 

:argh:I decided to try and wing it with this since I havent been able to obtain any advice.I did a fuel system purge and after recirculating the cleaner a bit I ran about eight gallons of diesel with 20oz of Diesel Kleen(blows my mind!!) I was hesitant to get on the interstate but i felt like if I was gonna let it really do its job I should be cruising at a nice steady pace.When I got on the interstate i was barely able to get up to a safe speed and was blowin so much smoke I couldnt see anything behind me but it was feelin a little stronger already.I pulled off and "backwashed some Diesel Kleen through my fuel filter then put it back on,NOW WERE TALKIN!!! I got NO SMOKE when I started it back up and felt a little more power.After crusing out of town a ways and by now I was holdin a comfy 65 and only blowin black smoke when I stomp it.I brought her on back into town and got off the interstate and was actually passing people in town instead of smiling while frustrated people go around me.I grabbed some more of the Diesel Kleen(came with the truck and I never used it....duh) and a bottle of Clean Diesel the formula specifically for cleaning your fuel system by the same company as Diesel Kleen from Wal-Mart and I feel pretty confident it will be running as good if not better than before in no time!! :jump: