gmc suburban misfire
i have a 98 gmc suburban k1500 4wd 5.7 vortec. i had a misfire and overheat problem. i replaced the upper and lower intake manifold gasket, replaced old spider injectors with new multiport injectors, i also replaced the distributor cap and rotar, spark plugs and wires. i am still getting a misfire on cylinder 3 and 6. i hooked a fuel pressure gauge to it and it held pressure at about 55 but when the key is turned off it drops fast to zero. anybody have any ideas what else could be the problem?