Engine Stutter During Idle.
 

Hi all, 2008 lx-p 206k

when my car is parked and idling and I accelerate to 3000 rpm for a minute, the engine starts stuttering and the CEL flashes. The car drives normal. I can switch gears up to 4000 rpms and the car won’t stutter. The stuttering only occurs if I hold the pedal at 3k for 30 seconds during idle. I get the P0300-304 codes. I’ll let the car sit for a day, start it up and the codes are gone. I can drive to and from work with no stuttering or codes. I replaced the throttle body. I have new spark plugs installed (NGK). I checked for air leaks. No leaks. I cleaned the IACV. I should be able to rev at the max and hold it without any stuttering. I’m thinking it might be the coils. I’m curious if anyone has experienced this. I would greatly appreciate anyone’s help. I can’t pass inspection in NY until I get the catalyst monitor ready, but I can’t do the procedure until I get the stuttering corrected.
Thanks in advance.

Did you look at this?

Why use white for letter color? No one wants to try to read it that way.
P0300 is for misfire. If last number is consistent P0301 then cylinder 1, if P0302 then cylinder 2 etc.
Could be intake manifold gasket?
Could be head gasket?
Could be many things and the only way to find out is to continue to test.
If it is a coil then switching position of the coil can help isolate it (if coil over plug)

Sorry about the font color. For some reason, it wouldn't let me put it to black. I was driving the car with no issues. It failed inspection because the catalyst monitor wasn't ready. I drove the car all week shifting at the 4000 rpm mark and didn't have any issues. I couldn't get the catalyst monitor ready so I found a video that said to rev the car to 3000 rpm for 3 minutes straight to get the catalyst monitor ready. That's what I've been trying to do but when i rev the car to 3000 rpm during idle, the CEL flashes and I get the P0300 codes. I just replaced the coil packs and tried again. Same result. Flashing CEL with the P0300 codes. I can hit limiter without issue, as long as I don't hold it at a certain rpm for 20 seconds/ I sprayed the intake boot, replaced the throttle body, cleaned the MAF and IACV. I sprayed around the manifold, throttle body and no change in idle. The ten day inspection ended Friday so I don't know what to do at this point. When I drove the car, I noticed while shifting from one gear to the next, the rpms are slow to drop. I have to wait about 3 seconds to shift into gear. I assumed the throttle body was going bad. That's why I replaced the throttle body.

You need to do the drive cycle for that monitor to set. May need to do it more than once. Is anything else not ready especially O2 as that would need to be fixed first. Also a sluggish O2 can keep the monitor from running.
You say "That's what I've been trying to do but when i rev the car to 3000 rpm during idle".
What? From idle maybe?

Oh well