1999 Chevy Blazer LS 4DR/4X4 @ 210,000 Miles

I'm experiencing an engine misfire that is mainly noticeable during a warm idle. Occasionally it'll start hard, cranking 15-20 times before actually starting. The tach needle is shaky and shakes when starting (not sure if this is relevant or if the tach is junk). It seems to drive okay but when it's parked and idling, I can feel the whole truck shake at random, and it sounds like a random engine knock. When I lift the hood and let it idle, the knock seems to be coming from the passenger side toward the top. But again, it does at a higher RPM, nor does it sound like the knock is in a rythem. It's at random.

Here's a list of everything I've replaced over the last 20,000 miles:
Fuel Pump
Fuel Filter
Distributer (entire assembly)
Mass Air Flow sensor
Crankshaft Position Sensor
Catalytic Converter/Muffler/Tailpipe
Ignition Coil Pack
Spark Plugs/Wires
Water Pump/Fan Clutch
Air Filter

if I think of anything else, I'll add it. Only check engine codes are the random misfire (p0300) and the bank 3 sensor 1 02 sensor, which was replaced and none of the replacements I received worked, so I just disconnected it (but the problems began before I did any exhaust work on it).

 

could be a lot of things, did you do a crankshaft relearn after installing the Cranks sensor? what brand cap rotor wires, plugs. These trucks are fussy and only like acdelco tune up parts. A spark plug wire could arcing( you can tell by looking at them in the dark with engine runing. I had a skip that drove nuts on 2 different occasions. One was a loose plug that was snug when cold but loosened up when the engine got warm. the other was a plug wire that wasnt fully seated on the plug. A couple to get you started in your search

 

2 problems. Engine knock and engine miss. You are very unclear on when it knocks and when it misses. Disconnected what?? Again, did you do the crank sensor relearn after replacement? Please start again.

Early on in my Blazer experience I had a lifter collapsing at idle and making a clacking noise - along with a false P0304 misfire code. FYI mine had excessive bearing clearance and was losing oil pressure. Not that this is your problem, but it should be considered when your engine makes noises.

Post #1 here has a video of the sound mine made.

https://blazerforum.com/forum/2nd-ge...g-valve-87514/

 

Why did you disconnect the new o2 sensors?