how high does your boost get? any smoke? have you ever cleaned the turbo? oversize injectors? did it start doing this immediately after engine work or shortly there after?

 

any codes? sounds as though the ring in the turbo if sticking

 

yea a P0046 i think tc/sc boost silinode? The VGT is not working. we unpluged the wire to the vgt control and truck does the very same thing. we are changing the actuator on the turbo now with the one out the old turbo if that dont chang anything im going to take it back apart and clean the turbo. its a 07 turbo we just had to change it. it worked fine when we drove it sunday just befor we pulled the cab off. my had some antifreeze in the exhaust maybe with the turbo sitting on the table for 2 days i rusted a little idk just wishful thinking