random cylinder mis fire on 1999 Chevrolet Silverado 1500

check engine light comes on and engine runs poorly,code is random cylinder mis fire,light will go off on its own,and truck will run normal again,noticed if i pull out at high rpm's light will come on everytime,or put a strain on engine it will too.

If the check engine light is flashing, you are experiencing a misfire, and you need to have it looked at very soon, failure to do so may result in damage to the catalytic converter. See this article about check engine lights, and what to do:
2 more answers
Did you fix your problem? I'm having the same issue and have done the same things you have.
check fuel pressure bad fuel pump