Another issue with turbos misfiring is that with improper spark, your spark plug could be blown out. It is very important for a good spark with proper gap (smaller than naturally aspirated normally). I would keep the iridium style plugs but definitely change the coils and wires (especially if they haven't been changed in years).

 

My 4 gear clutch is slipping at 4000rpms and my 3 gear clutch is not slipping but won't change gears how it should. The problem about the car stalling I think has to do with my Tune.