I put redex and an oil top up in my car last week and ever since ive had problems. I have rode it out and used all the fuel and have just topped up with v power. Just took her out and its still hesitating. It tried to cut out on me and the check engine light came on temporarily so i pulled over. It then cleared and now is driving fine but keeps hesitating still and by hesitating i mean it keeps losing power and bogging down.

Any ideas where to go from here. If not shes being sold as she is as my baby is due in next week and i cant devote the time to her. its a 94 wrx sti ver1 in black, few mods.

Help appreciated guys

 

forgot to add, the redex was a standard size bottle and the oil was semi synthetic 5w 40 which i believe is correcto