Hi guys I need your help. I have a 1980 240D that I love but just today has been having horrible shifting issues. This occurred after I replaced the 3/2 valve (my mechanic's recommendation) since mine had a worn lever. Ever since then it has been shifting very late and hard but will upshift whenever I take my foot off the gas. It was shifting fine before but would already be in 4th by 25mph which seemed low to me. It also used to have a slight flare. I'm thinking it could be a vacuum leak but have no idea where to begin. I've checked all the tubes and they seem fine, my doors close without any issues, and when I unplug the tubes from the 3/2 I can hear a distinct hiss.

Any help would be greatly appreciated!!! I don't have the money right now to take it to the shop and don't want to cause any permanent damage to the tranny.