hey guys...i was just wondering how can i do a vacuum check up at home..i really dont have much money to spend...recently my mechanic changed the knock sensor even since that p0171 & p0174 came on..before that i had restricted performance but it was just a coil.. im suspecting whether its the manifold.. car hesitates when im doing 30-60mph. rpm goes up n down...jumps... so any idea? any help?

 

https://www.jaguarforums.com/forum/s...ics-faq-52720/