You probably have a vacuum leak. It should be a diyer type of repair - the hardest part is finding the leak. I would suggest purchasing a vacuum pump kit - the "MightyMite" which is available about anywhere is a good one. Also, look around REAL good under the hood in the vicinity of the brake master cylinder and you may even be able to find disconnected vacuum lines or broken rubber vacuum line connectors. It would help too to have a manual showing all the vacuum lines and their colors. If it is not a vacuum leak then it is the shut off mechanism in the fuel injector that is controlled by vacuum. Also, do a search on here on vacuum leaks.