I do not have an answer for you either, but would suspect what the shop did, or maybe nicked a vacuum line somewhere???
Anyway welcome to the site. If you take a few moments and re-visit your User CP and edit your details to add the information on your truck and your location. That will help us help you when you have a question or are having a problem with your truck for future posts.
There are a lot of talented people on this site, so if you have questions feel free to ask, and I am sure someone will be able to help. If your looking for some accessories check out our vendor section and may the modding continue or begin