I have got a linear engine acceleration problem. There seems to be either a air, fuel or spark starvation above 4K RPM. It climbs to max revs but its just not smooth increased engine revs.

Just a thought in delivering any possible help thanx, I have noticed quite a vacuum buildup in the fuel tank, when filling up. Is this normal in MK1 Punto's?
If it is, I still have the original coil pack on the car and in 2011 the HT leads were replaced. The plugs were changed at the beginning of winter so what could the problem be? Have recently had the rear shocks replaced and timing belt replaced and it made a world of difference thankyou. In conclusion the straight and linear acceleration is vastly improved after the timing belt was done, but still the car's acceleration is stunted by some sort of starvation of either fuel air or spark it seems.

One new fuel pump sorted the problem, but still the vacuum builds in the fuel system and all the problems return, so I will never fill it up and run to empty without releasing the vacuum in the fuel tank. No more hunting or starvation of the engine.

Blocked breather or needs new fuel filter (service item that is usually neglected). Very dirty fuel filter may eventually cause fuel pump to fail.