p0300 is killing me

[76zolly]

Morning y'all, The other day my 99 hoe with the vortec 5.7 started misfiring bad. I went to the part store and they told me P0300. multi misfires. so I changed out
plugs
wires, cap, and rotor
camshaft sensor, crank sensor
Spider injectors.
nothing has changed.
I replaces the coil and still no change.
I also blocked off the egr valve and still no change.
I did pull off the valve covers and all the rockers are moving fine.

Can someone please help.

Thank you

 

[jeremiahoperacz]

This is killing me too, did u figure it out?

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[jeremiahoperacz]

Pretty sure ive got mine figured out for the most part, last piece i put on was coolant air temp sensor. Light will sometimes flash but doesnt affect performance anymore. All new fuel system and ignition system plus new computer. Drove me up the wall but now it will atleast go on the highway

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[97tahoe97]

Could be the timing or even the new parts you put in. I was always told to use ac delco or gm parts because the vortecs don't like certain brands. When I got the same code I put ac delco plugs in and fixed the timing then it ran like a dream and I had no codes

 

[jeremiahoperacz]

How do u change the timing?

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[SARNCAN]

This might help

 

[SARNCAN]

This may help

 

[cesaralatorre71]

You have a intake gasket leak

 

[Firematch]

What is the best way to check for an intake leak?