Engine Miss Firing

[shaky]

hello everyone im shaky new to lexus club, can some one please help, i have lexus is200 03 plate for 2and a half years now. around 9 months back i had a spark plug shot through the head and compleatly ripped the coil out. there was no threading for sparkplug to go in so i got a mecanic to wave his wond and he done a sort of recoil job. everything went well till today car has lost some power and is miss firing.i got car checked on reader it said random miss fire cylinders 1 2 and 4, 4 was the spark plug which shot out and was recoiled 9 months back. any how went home and opened cylinders 1 and 6 and swapped both sparkplug and coil. now if coil or sparkplug from cylinder 1 is no good then cylinder six should not fire now and cylinder 1 should fire. so i went back to get it read and nothing changed cylinders 1 2 and 4 were still miss firing.all this took place in bradford while on holiday.so i decided to drive the car back home 258 miles to london. was flying between 80 to 100 miles down the m1 the car was smooth no over heating no ratalling just slight less power in pickup.from driving experience keeping the pedal steady or giving throttle power mood changes and can push forward as if coming back to normal can some one please help thanks shaky.