01 F350 7.3 Trouble Starting

Truck has around 150,000 miles on it. Around 70,000 I took had a meltdown with the wiring harnesses on the engine and Ford replaced them supposedly, but one of the 3 times it went in the shop, they said I had an injector bad and they replaced it. I talked to a friend of mine who is a trained diesel mechanic and he said that they should never replace just one injector because it can cause others to leak. Well now I'm having big time troubles with this truck and I was wondering if ya'll think it has something to do with the injectors or any other suggestions. If it gets below 50 degrees or the truck sits for more than 8-10 hours, it take at least 3-4 minutes to get it started. If i plug the block heater in however it cranks like a champ. Also, sometime when i'm sitting at a stop light or sitting still, the RPM gauge when idling will dip down and then right back up to normal, the truck kind of putters and then starts white smoking for a little bit. I have lots of trouble keeping oil in this truck. It probably burns around a quart a week. When i took it to ford right before my 100,000 mile warranty was up, they said there was nothing wrong with the truck and they couldn't find where the oil was going. Sounded like typical BS to me, but the oil has been changed 3-5000 miles regularly and i just installed a new fuel filter last week to see if it helped any and it seemed to work for about 3 days and then the truck started smoking again. Any help or suggestions would be greatly appreciated.

I'm new to Ford's, I just bought an 89 f250. I didn't get any help to my problem on this forum. You should head over to www.ford-trucks.com (http://www.ford-trucks.com/) They will help you!

Check your glow plug controller, oil consumption may be passing into the fuel system by your "O" rings on the injectors. As far as changing all injectors at a time , not realistic unless they have failed. Replacing the "O" rings is a more realistic repair if it is determined to be the problem.