engine hesitation and weird oil pressure

when im driving at 2500-3500rpm the engine will lagg. it feels like im letting off the gas and pushing it. and my oil pressure will go to 80psi and then sit there for a little and itll drop to 70, and the needle sometimes bounces back and fourth. there is a kink in the line that used to make the oil pressure get stuck, but i unkinked it, could the line be making the oil pressure higher then normal? its the stock autometer mechanical line. and whats causing the hesitation? i got a rebuilt head, and 120k miles on the engine.