Vortec 350 engine misfiring

[Stepside_fever95]

My 1999 350 vortec suburban k1500 has been misfiring under slight acceleration for over 3 months now and is getting worse. The code reads multiple/random cylinder misfire (p0300).
My fuel pump went out and left me stranded around 2 months ago so i put a new delphi pump on it and a new fuel filter. That didnt fix it.
I figured my distributor cap and rotor button, being a parts store brand and lower quality than oem, needed to be replaced, so i put new ac delco parts on it yesterday and the problem still persists.
My next thing would be the coil wire, as im pretty sure it is electrical related.
Any help or ideas are greatly appreciated. Id hate to spend money on parts that may not fix it.

 

[Jrgunn5150]

Mine is throwing misfires from the leaking spider, shine a light through the TB and see if its wet or badly carboned up

 

[Stepside_fever95]

Ok ill check that out, thanks!

 

[Stepside_fever95]

It looks like there may be a little carbon buildup.

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[Jrgunn5150]

Yeah that's how mine looks, I'm doing the MPFI upgrade Saturday

 

[Stepside_fever95]

If changing out plug wires and spark plugs doesnt help, then ill probably just replace the spider.
After talking with my dad, were thinking some coolant may have possibly gotten to the plugs when my intake manifold gasket blew. That could be it i hope.

 

[Jrgunn5150]

Well when I take mine apart tomorrow I'll update you with pics and stuff, 300 is a lot to throw away lol

 

[Stepside_fever95]

Yeah i know. How much do you have to do and what all do you have to have?

 

[Jrgunn5150]

The upper intake has to come off, along with the associated wires and hoses.

Looks like just wrenches, sockets and pliers to do the job. You'll need deep sockets to get the intake off

 

[Stepside_fever95]

So id have to do that anyways. What about the parts for the mpfi conversion?