Ive been having issues with my monte acting as if it's choking or having loss of power maybe, it's more noticeable now when I cold start and the car acts groggy or maybe can't breathe and then after 30secs or so it'll eventually whine down, but once you actually try to accelerate and gain speed it feels or seems as if it's muffled or doesn't want to gain speed due to something restricting the acceleration.

I was told before it could be anything from fuel filter, pump or catalytic converter. I drive it almost everyday to and from work knowing how to drive it under the condition it's in but I manage. Today I removed the converter and welded a straight pipe in hopes it would allow it to open up more but it's still doing the same.

Also went to AutoZone for a scan and it's says to replace intake plenum and gaskets, with codes for:
P0300 Multiple Cylinder MisfireP0135 O2 Heater Circuit (Bank 1, Sensor 1)
P0141 O2 Heater (Bank 1, Sensor 2)
(*Both due to removal of converter I think)
P0332 Knock Sensor 2 Circuit Low Input Bank 2
P0446 Evaporative Emission System Vent Control CircuitP0452 Evaporative Emission System Pressure Sensor/Switch output


Any help, input, feedback, or mechanics from my fellow MC enthusiasts would be greatly appreciated!!!

 

With the misfire code I would first check the ignition system. How are the plugs, have the wires been changed ? Finding someone who can tell you which cylinder misfired and how many times would narrow down the problem. Unfortunately most part store's don't have this type of scanner.

 

I'll second that. You really need the car to be scanned by someone who can read live data to try to give more insight as to what the inputs/ output are doing in real time. Codes can be a helpful place to start, but P0300 has a laundry list of potential causes. You've also got a good number of total codes (even ignoring the O2 codes), so its likely more than 1 problem. IMO its too much to accurately diagnose with the data we've got here.

 

The P0300 code is leading me to believe that the Ignition Control Module has failed. Happened to my Monte last year. A good way to check is to unplug the spark plug wires at the coil pack and check if there's spark. Also, I would check the firing order while doing that. Sometimes, the spark plug wires could be connected in the wrong sequence.

 

I'd change your coil packs. I had a cylinder 1 misfire after the second intermittent code. I replaced all of them. Kept 2 as spare and the pack that was giving issues I tossed. No more misfires. Be sure to put heatsink grease on them before putting them on the ICm. I replaced the ICM about 2 years before those, my ICM issues was cranking but not spark.