Suck my DX

i got a 91 civic hatch with a jdm b16 swap/pr3 ecu...so ill be drivin on the freeway in fifth aand if i downshift it and get on it a couple times it throws out the cel 22...it doesnt do it if i make drag runs so im confused...what it does do when the light comes on is: engine runs funky...revs very slowly...wont go over 7,000 rpm..usually pulls hard till about 8,000...as soon as i turn it off and let it chill for a like only two minutes,then turn it back on its fine again..so im like wtf...the guy who i bought it from says that its a vtec code for oil pressure but didnt exactly know what the deal was..he said he encountered it as well..and it didnt start doin it till he installed the vafc(would that even have anything to do with it?)...i changed the oil and oil filter today just to see if it might make a difference..i dont know what kind he was using but i put in 20w-50..the light did not come on after i changed the oil..but i also did not drive it hard..i just dont want something to get majorly f'ed up in a car i just got last saturday..if anyone has any suggestions or has dealt with anything like this before..please help me out..ANY advice will be appreciated..thanks.