A big thanks to everyone for all the info.!
I was able to troubleshoot my P1640 code on my '95 bonnyville ssei.
The car ran good but did not pull hard,I picked up a used boost control solenoid to confirm my suspitions and WOW! does this thing move now!
P.* I bought this in June and it ran okay but the check engine light was on when purchased.The other codes P0101 MAF & P0123 throttle position sensor got my kickdown & overdrive to work.I also changed out the computer(shop said P 1640 QDMI failure)
This car is now fun to drive, it has 292 000Kms.but you'd never know it.
Sorry no pics yet, it is black with grey interior fully loaded.
2003 F150 7700
1991 Dodge Spirit
1968 Plymouth Barracuda 340 4 spd.