Was coming home one day and after passing a Sunday driver I heard this fluttering sound coming from under the hood that never was there before. It only happens after WOT under boost. As soon as you let off of the gas you hear a short flutter. Half throttle and mild boost doesn't make it happen. Sitting still in neutral pushing pedal to the floor doesn't do it. I have tried soapy water as well as other things but nothing helped to find the cause of it flutter. Sent Procharger head unit and Big Red Bypass Valve to be checked and both were fine. Since removing all intercooler tubing I have purchased a boost leak detector as well as a smoke machine that goes up to like 20 or 30 psi if needed with all kind of attachments. A while back I had to replace AC condenser on other vehicle so I bought vacuum pump and manifold gauge set to do it myself. That's when I remembered something about the truck. I hardly ever used the AC so I can't tell you for sure what happened first but the AC was acting funny. Sitting under carport you could start truck cut AC on and it would work fine it seemed. Sit there for 3 or 4 minutes then pull out for a drive and within a few minutes, BAM the blend door would change position and hot air was all you got. Nothing I did would make it go back to putting out cold air. I replaced blend door actuator and fired her up UNDER CARPORT and cold air once again. I cut it on and off multiple times as well as going from vent to defrost to floor and everything was fixed or so I thought. Drove to work the next morning with outside temperature around 70 to 75. Air worked great. Got off work with temperature around 90 and truck sitting in hot sun. Fired her up sit there a minute and cut the AC on. Nice and cool working like a champ so I pulled out of parking area and headed home. I didn't even get to third gear when that dreaded sound of the blend door hit and back to heat again. Long story short if truck is cool and outside temp isn't to hot AC works. If both truck and temp are hot even with cold engine AC don't last long. So I cut all air off coming into truck cause just opening fresh air vent was the same as cutting heat on. The next day it did the same thing. I guess I got a vacuum leak somewhere that is causing AC not to work properly BUT could it also be causing the fluttering sound I hear after boost. Seemed like I wasn't getting as much boost also according to boost/vacuum gauge which is tied into vacuum system. Any thoughts will help. Thanks