Ford Super Duty (1999-2016) :: 2005 F250 - Hesitation When Give It Throttle

I bought the 2005 F250 6.0 Turbo Diesel with 67,000 miles on it last March. It has given me gave me absolutely no problems until now. In the last 2 weeks I have had it plugged in when it was below 32 degrees outside. Otherwise, I just remote started it every morning and let it run for 20 minutes before I left. In the last 2 weeks, I have noticed the same problem whether it is morning, afternoon, or evening and it happens at different times. I will be at a standstill at a stop light, stop sign, or parked in my driveway when this occurs. Sometimes, and like I said, "sometimes", it will hesitate when I give it throttle. It will quickly respond after maybe a second, but the hesitation is still there. It only does this on occasion!

I work for a Lucas Oil distributor, so in the winter I ran the "extreme diesel conditioner" through it with a tank of diesel about every other week. I also used the fuel-injector cleaner at every fill up. On "ONE" occasion, and like I said, "ONE" occasion, when it hesitated at a stoplight, I looked in the rear view mirror, and noticed a short burst of white smoke, and then it took off. It has not done that since. I took the EGR off and cleaned it and it seemed okay until 2 days later, then the same hesitation came back, but like I said, at times!

I replaced the air filter and since then I have done nothing. I am now being told to check the coolant level in the resevoir. When I un-screwed the cap the cap, there was pressure in there and the fluid was about 1/4 inch low from the line. I was also told to check the filter on top of the block, but I have not gotten that far. Ford says it is the EGR cooler system! I have "NO" check engine lights!