hey steven, def go see scotty. man has forgotten more than i know.
id also be checking the coil packs mate, 4-5k is classic coil pack break down. if youve plugged the original boost solenoid back in, this is when it switches to 7psi, and the coil packs arc out thru tiny cracks to create a fuel cut like break down.
if your afm is shagged you normally cant run past 2k rpm...
i say normally because with most 20 year old engines, you will fix one gremlin and another will pop up.
let me know if you cant fix it or scotty is busy, im in cranbourne mate, and had a 33 auto just like your self.... they have all the standard 33 issues, plus some added ones on top!