lately i have been having a trouble where full throttle pulls thru 4th & 5th gear will pull hard to about 2400rpms, then just die off, you can really feel the power start to dip, and the boost will drop from 35 to 29psi...it used to hold right at 35

now before anyone says its a boost leak...no, it will hold the 35 psi steady when i get to 6th gear...but 4th and 5th for some reason have a loss in power and boost. at first i thought maybe clutch slippage...but i can go from low power in 5th gear, hit 6th gear pretty hard and when the rpms drop, the fuel starts pumping again and it will pull like a freight train and hold the 35 psi boost.

think maybe the van aaken box has issues? maybe an ecm issue???

any ideas fellas!!! please help me out here

 

Try the Map sensor, I had a truck that was doing about the same thing and a Map sensor fixed it

 

Is the fuel pressure staying up when it does it?

 

unfortunately at the time being im trying to gather parts to get a fuel pressure guage back in the truck...the electric one that was in there broke and i took it out...trying to get a mechanical gauge back in there ASAP

also i know i need to change my fuel filter, its getting to the that time again...that could def. have an effect as well

 

I had the same problem some time back, found out that time I had a Bully Dog torque dog timing box and it quit fooling the computer. I would suspect the fooling part of your box has failed, check that before anything else.