problem solved

[88Racing]

Originally Posted by grantlshiell

Finally after a year i figured it out. After installing my pheonix chip i had throttle response problems with the higher horsepower tunes. They were always jerky in the lower rps to the point where it wasnt even drivable. This past weekend i changed the belt driven vacuum pump on the motor because the bearing was squealing. Low and behold my problem went away with the new pump. Does anyone knowwhy that pump would affect the throtle response? By the way i would have sold my truck by now without that chip!

Vacuum leaks can be a pia especially at lower rpms with a load applied....

So therefore if it was replaced with the bearing squealing then the seal already had gone south probably at the same time the bearing started to go but it wasn't making noise yet....