Why does the engine rpms flutter and sometimes won't throttle up enough to move on 2006 Ford F-250 Super Duty

Especially while sitting and idleing I will notice the engine rpms fluttering and even while driving around town at half throttle I notice some fluctuation. Sometimes after stopping at a stop sign, it won't throttle up (no response on the footfeet pedal). Sometimes you are in the intersection before you know it's failing you, making for some dangerous situations and making other driver very mad at you. If you kill the engine or shut it off (in an attempt to reset the computer) it won't start again. Sometimes the engine code light comes on, and sometimes it doesn't. This problems has been going on for more than 2 years. I've had the pickup in 4 times and they replace turbos (twice), and egr vales (twice), but the problem keeps reacurring. It was it the Ford shop from Wednesday through Saturday last week and came home with a new egr valve and trubo. It sat in my garage over the weekend and on Monday after hooking it to my stock trailer and hauling 1 load of cattle, it was fouled up again and unuseable.

by in Sisseton, SD on July 19, 2013
1 answer 2 comments
ANSWER by on July 19, 2013
do you know what code or codes set when engine light comes on?
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COMMENT by on July 19, 2013
Taken right from last weeks repair order, it states that the Ford shop found code p0299. That's this last time. Besides the other 3 times it's been in the shop, I've had local mechanic read the code and reset the light at least a couple of times (because I live at least 45-50 miles from the nearest Ford shop), and I couldn't tell you what the code was those times. But none of the Ford mechanics I've seen and talked to have ever seen the problem (fluttering and not idleing up) that keeps reaccurring with my pickup.
COMMENT by on July 19, 2013
p0299 is turbo underboost. this could have a wiring concern or exhaust pressure sensor or tube problem. you will have to get to a reputable shop for diag as you have had it to several shops. check this web site to see who is local to you. need someone strong on diesel diag.