92 chevy blazer. 5.7 tbi. just purchased. gave tune-up with msd 6a,coil,wires and adapter. truck starts then shuts off when it warms up. also originally was given wrong plugs at auto shop and engine knocks now. was running a little rough before tune-up and now have problems. also rpm needle is at .5 while idling. shouldn't it idle at 1.0? if so how to adjust idle speed. new to this model sorry for so many questions.