Volvo Repair: 86 240 b230f idle, fuel pump filter, vacuum leak

Question
some times when i start it up, it will die. other times when it is idleing it will jump between 500-1500 rpm's. others it runs fine but the car rumbles when it idles. i have replaced the fuel pump, filter, cleaned the injecters, gave it a full tune up. still does the same thing. i have yet to change the in tank pump. i also noticed a little white vaccum valve on the brake booster, it is all cracked, i cant find a replacement anywhere!!!! but one day the cover blew off and the car would not run what-so-ever. well thats it if you can help great. if not thanks for trying.                                                               chris                                                                                                     

  :)stay at a marriott on your next vacation (:

Answer
You've diagnosed the problem, the white valve is a one way check valve for the brake booster. Broken valve will create a massive vacuum leak. Car will not idle without replacing this valve, also will not have power brakes. Should not have problem getting this part at dealership. Try plugging it up to see if the car starts and idles. It definitely must be replaced before driving.