stalls on incline

[igor]

my 89 240sx 113k wants to die out when accelerating on an uphill incline from a stop. when stopped in such a situation i give it gas to go as i do normally but rpm's drop and it sometimes dies out completely. i have to give lots of gas (3000+ rpm) in this case to get it going. two factors may contribute to that though: i recently switched from regular to super fuel. perhaps this is a timing issue?? also i pulled out the aiv and plugged up all vac and exhaust hoses. spark plugs and fuel filter just changed a week ago. any ideas would be greatly appreciated. thanks!