Diagnose engine misfire problem

I plan on order a fuel injector from partstrain.com:

http://www2.partstrain.com/v5/products.php?N=4294964613+1589+4294967162+5657

I'll do that as soon as I figure out the exact item to order. Right
now, the same SKU# SIFJ478 is used for both Original Equipment #
4861238AA and Original Equipment # 4861238AB, which is confusing.

I need advice on these "Standard" made injectors. Are they good? How
do "Standard" auto parts compared to OEM parts? Is "Standard" just
"standard", or it's actually a trade name?

Also, please tell me if anything else I can test before change this
because I don't want to change it to find out it's not the one causing
the problem.

My previous question about "should I take out both the upper and lower
intake manifold to replace the injector" did not get any answer. Any
help here? Thanks.

 

I am so disappointed right now.

Just feel disgusting some how in my stomach. I am sorry for saying
this.

I just replace 3 fuel injectors, for cylinders 1, 3, and 5.

Same problem!

The replace and hope method just doesn't cut it.

There has to be a way to test these things the right way.

 

This is a very funky problem. I took it to an auto service center.
They have been looking into it for 3 hours, and haven't figured it
out. They have changed the sparks and wires. Also test pressure
again and they said there's signal in the fuel injector electric wire.
I'll update if they find anything, or any news on this.

I am sorry for the last post. It was a moment of frustration. I
didn't mean to aim that at anyone. You're all been very nice and
helpful.

 

The mechanics gave up on this. I'll go to the dealer next.

 

So, I took it to a Chrysler dealer. Initially, they asked for $100 to
look at the engine problem. Later, ask $250 to open it up and look
inside. They still can't find out the problem. They suggested to
open more (cylinder head, or something like that) for $400 or replace
the engine for $3600 (with 3 years warranty). They also mentioned of
the cost of rebuilding would be $2500 with 1 year warranty. That's
after 4 days of looking into it. I paid them $250 and took the car
home.

I took it to a mechanic that I know, couple hundred miles away. He
said the knock appears to come from a cam that developed a hole in it
(due to some manufacture defects). He replaced the engine. He said
he opened it up and it was the problem.

The car runs fine now. I wonder if that problem can be fixed or
replaced locally to lower the cost instead of replacing the whole
engine. Anyone familiar with this mind to share?

 

why not just replace the cam and lifters???