geo metro

Hi i have a 92 geo metro the egr valve blew the plug out of the back of it
burning holes in 2 vacume lines. i replaced the lines and the egr valve the car was running withthe bad parts on it ran bad but ran, after repaceing the parts car won't start if it sets for awhile a
it fires once and then jest tuuns over but won't fire timings right, getting gas ,unhooked battery over night to reset computer still won't start driving me nuts aany ideas ? also why would it blow the plug out of the egr valve to start with

thanks teddy b