Aloha, I could use some help with my Detroit 6.2 motor with a th400 transmission. It's a 1986 Silverado. I should have checked vacuum first. I did replace the governor and vacuum modulator to the transmission. Upshifting is a problem therefore I figure it is my vacuum now that I replaced the above noted parts. I replace the rubber hoses that went to court and then split to what I believe is the vacuum pump behind the air filter. Couple questions. Is that a port that I'm mentioning for a valve of some kind? The vacuum pump behind the air filter has none too just a little bit of vacuum suck to it. Is it safe to assume that this is the problem?