You need a resistor in series with the fet gate to limit current from the 555 and so as not to try and switch it at too high a rate, 10 ohm ought to be ok.
Also a 100nf decoupling vap across the power pins of the 555 might help, and a 10nf from pin 5 to ground, also route the wires to the inductor and output ground direct to the power source and put a 100uf or 470u cap across the source, and route the power supply lines to the 555 separately back to the power source, basically everything to the right of the 555 with its own power lines, and everything to the left with its own power lines back to the supply/battery.
If you wound the inductor its windings must be tight and close to the core, its leads to power and the fet drain must be short, to avoid parasitic oscillations.