Right newish to scoobys and need help,ive a version 3sti,and last week went for a drive,all running fine when home and parked up,however next day on starting it only ran on 3 cylinders(cylinder at rear nearest turbo) have changed the plugs( pfr7b) had to buy a new genuine lead as old one was stuck in and snapped when force was used,and have replaced coil with another second hand one off natty from the traders section,but its still bloody missing all the time,any pointers would be greatly appreciated

 

Compression test?

 

Compression test as red said, pull the plug out and take a look. see if is oil fouled.... compression test at this stage to rule out piston/ring damage..

 

Any fault codes - mine was doing this recently after I tried to remove the fuel evap system. Could just be a leak but fault codes would help point you in the right direction