ka running slugglish

[S13_PoWar]

my car seems to be slugging a lil bit. i just put a tiny bit of 87 gas because i was being stupid not to fill it up. i then went to the gas station and filled up with preminum. i thought that would kill all dat 87 but it didnt. the car runs fast and slow at the same time. could it be my timing being advanced? and also does regular gas foul your spark plugs? any help would be appreciated.

[eastcoastchaos]

87 shouldn't foul your plugs. higher octane gas burns slower and is more resistant to detonation but our cars in stock trim should run fine on 87, or at least all mine have on the few occasions i've run the cheap stuff. Are your plugs fouled? do they all look the same?