Misfiring Toyota corolla

[Joeyman828]

My 2002 Toyota Corolla accent is having a few problems, wondering if anyone could help. It’s only firing on three cylinders, have removed the spark plugs and all have recently been replaced, it’s definitely on cylinder one as when we removed the spark plug it was clean but the others had been used a little but recently all replaced there seems to be a bit of oil in the coil pack for some reason, thanks in advance guys. When driving also makes a ticking noise when driving but can still get up to around 80, engine light comes on to, but haven’t got a diagnostic tester, tia