I have a 98 Chevy 350 Vortec that does not want to start and back fires when its cold and runs rough when it finally does start. fuel pressure 62 psi. I have change plugs wires rotor cap and button it has no codes runs fine once it's warm just seems like it has low power I am lost this point please help

 

I would check the fuel filter, maybe clogged, there like 6 bucks at oreillys, you can get wix but its like 14 bucks i think, also I would run a compression check all 8 cylinders, you have to get a gauge and the right plug to get it too work, what your doing is checking compression when you barg the engine over, should be around 150-180 compression on each cylinder, on my 97 gmc 305 i had 165 on one side of the engine and 175 on the other, which is fine, that is a compression check what i just told you there, also you can do the leak down check with the same gauge and hook it to a compressor but you have to get each cylinder to hold air (barg the engine over and get a top dead center on each cylinder), then pump about 35 psi in each cylinder and watch for bubbles in your radiator basically what your doing is making sure you dont have a crack head or a crack block. But thats the first things I would do before I took a mechanic anyways hope this help.. also make sure your MAF( mass air flow sensor isnt bad), you can get a use one at the junk yard.

 

Thank you much. Filter is my next step. I replaced head 6 months ago. And compression checks out fine