very weird problem, detailed explanation!

this new problem happened twice in two weeks and i cant figure out what is causing it. basically the rpm gauge starts acting erratically, moving all over like its dancing to music, notice that the idle of the engine is not changing. right after that happens the car misfires badly and idle is at 0 and can doesnt wanna move at all. it happened once before and i suspected one of the coils were bad and i had a back up coil so swapped it and it went away and car drove fine. now at WOT i hit a point where around 4k-5k the car bogs and wont revs past that in 2nd, 3rd or 4th. notice this happened two weeks ago and i drove the car few times since then and today few blocks from my house it happened again, i turned around and i made it home. same exact thing happened. i drove it at 0 idle and it smelled really bad like sulfur or something alike.

i have installed new spark plugs and evo coils so we can rule those out, i have a code p0300 that i cleared and the check engine light came back, i havent scanned it yet but i have a feeling its the same code again and hopefully its not another code.

i really would like to fix this, i was gonna go after the list of things to check for p0300 but this idle problem is throwing me off and im not sure whats causing that.

what causes the idle gauge to dance like that ??

im open to any ideas, just let me know what to check next and i will do it