1. Could be faulty oxygen sensor that screws up your air-fuel ratio readings.
2. If you have replacement ECU or piggy-back installed and you have put in new tuning bits, could be the settings/mappings need to be checked
Well, it has been ages since I talk about tuning my car. I did ones when my HKS bov kept stalling my car. That was when the car was completely stock with only boost controller, intercooler piping and de-catted. Speed...