I have new problem as of the other day i was 4th gear and noticed i was getting no boost i floored it and the boost cam on but only after 4500 when 2nd tubo comes alive......then later tried again and it got boost? i was then driving last night 1,2,3rd gear everything good then 4th i had no boost i shifted to 3rd and boost came back..then shifted back to 4th and had boost??? .........what could this be?