95 4.3L Vortec 'W' - Where to go next?

[Mechanicapped]

1995 4.3L 'W' Vortec

166,785 miles

Replaced:

spider assembly
nut kit
manifold gasket

This eliminated the fuel smell and improved gas mileage from about 10 mpg to about 18 mpg. Since it still missed out a lot, we went further and replaced:

spark plugs

This created a big problem. The 10 mpg gas mileage returned, and while it didn't miss out as it had before, it did then start missing out from 0 – 20 mph. The code at that point was P0302, Cylinder 2.

We then replaced:

wires
cap
rotor
air filter
fuel filter

No change in gas mileage. It still misses out from 0 – 20 and the code is still P0302. Now, it seems that the fuel smell has returned.

I have no idea where to go next. Is it possible that a plug isn't gapped properly? Could one of the plugs be defective? Does something need to be cleaned? Could something have caused the spider assembly to go bad again? Did the truck hear that I am waiting on a sizeable federal income tax refund?

Any input would be greatly appreciated.

[maxwedge]

Pull that plug out and look at it, maybe cracked on installation, you need to start there and work back.

[Gabe25]

Originally Posted by maxwedge

Pull that plug out and look at it, maybe cracked on installation, you need to start there and work back.

I agree with Maxedge. Sounds like you got a bad plug. However, if the plugs check out OK. Then you want to step back and check your fuel pressure. (60 to 65psi) and make sure you do a leak down check. Let us know what you find.

[Mechanicapped]

Helllll, yes!

It was the #2 plug.

This truck hasn't EVER run this good. I am so happy now!

I filled it up yesterday and am very, very eager to see what my gas mileage will be like now that I've finally worked out all of the kinks. Then I get to tackle the transmission. Short lived happiness, perhaps, but I'll take what I can get.

Thanks a whole lot. It's nice to go one day without worrying about what's wrong with my truck *this* time.