I've finally got my car back with a new used steering gearbox. I replaced the fuel filter but accidentally touched metal while changing the filter and blown my fuel pump relay. I replaced the relay (use) car started fine. Decided to replace the spark plugs and that’s when my hard starting problem occurred. I have new distributor cap, rotor, spark plug wires and spark plug within 5 months. What could be causing hard starting? Any help will be appreciated.

Thanks
R