Darren king

Hello to everybody as this is my first visit. I run a 92 WRX with a scorpion exhaust and air filter(no cats either).First question is my car is very unpredictable, sometimes when flooring it it goes like hell and others it reacts asif you have left the hndbrake on -an ideas? i've checked for air leaks etc.When your paying £900 insurance you want it to go dont ya? Sencond question is i am thinking the next upgrade is a remapped ecu but there are so many choices which works best without spending serious money.
By the way anybody fitting waterspray (diy) try a headlight washer pump to get more powerfull spray. Ive almost finished mine but am unsuere as whether to use a pressure switch or throttle switch.