Engine Mechanical problem
2004 Vauxhall Zafira 4 cyl Front Wheel Drive Manual 71000 miles

hi about 6 weeks ago my car engine light came on and then when i went over 30 it started to flash took it to be seen and he put it on the machine and it came back with misfire cylinder 2 & 4 he put new spark plugs in and new coil pack but engine light is still on and it has constant misfire now especialy when i put foot on the accelarator its making my whole car shake any ideas please.