Chevrolet Repair: changing fuel injector, chevy astro van, chevy astro

Question
I have a 1997 chevy astro van 4.3 v-6 240000 mi I recently have changed plugs, wires, dist cap, rotor and have run some injector cleaner through it. My problem is that I have a code that says that number 3 cylinder is miss firing. It idles smooth at start up when cold but when it warms up it idles rough. but when you start driving it seems ok. If you let it idle after it is warm the check engine starts to blink. If you rev the engine the light will stop flashing. I have also cleaned the egr valve. My question is how do you change the fuel injector and where is it located?
Any info would be appriciated.

Answer
Hi Vernie, You to remove the top of the intake manifold to replace the injector. This is the black plastic part of the intake manifold. If this doesn't fix the problem then your going to have to remove the cylinder heads and have a valve job done to them.

Have a Nice Day

Mark