I'm having some vacuum trouble with my 84 300D, For a while I have ahd a leak and my car would not shut off on its own, well i was told how to just bypass that 4 way connector under the hood and I got it to shut off with the key. I got under the hood the other night and used some rtv sealer on the lines to fix the leak, Well it worked great! the car shut right off with the key and my door locks worked great. Then a short bit later when i tried to shut it off it took about 15 - 20 secs after i took the key out to die. I bought all new rubber lines and t connectors for under the hood and its still doing the same thing. Where else should I check for a leak?