The Dreaded P0300 code :( idle fix anyone?

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2002 mazda protege
Hi everyone,

im new to this forum.

I have a 2002 mazda protege lx 2.0 L engine. at 99000kms (canada)
After visiting this forum, I've replaced my EGR valve, spark plugs, plug wires, ignition coils and still no luck.
It did give me a code p0300 before but its very intermittent.
Its very rough when idling and the rpms fluctuate between 2500-200.
Im going crazy on what else to replace or clean!

So this afternoon i did some inspection and here are some of the unusual things that i found.

1.) ignition coil # 1 the boot came off and upon inspecting the spring, it doesn't seem to touch the plugs when i put it back on

2.) air intake tube - theres a little crack on the flexible side of the tube (accordion like)

I did scan it with OBDII and freezeframe data and it gave me this:
fuel-sys OL fault-------> what does this mean?

can anyone please share their story?
 
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