If had something similar with my YRV turbo. Put in a Dsport thermostat which opened earlier at 60 degrees instead of the standard 80 degrees. Car would feel like it was kangarooing when it was warming up, like a misfire. Removed this and put back to standard it went away. Others have had issues with the igniter box corroding. The box connects up to the coil packs to help fire in sequence. The box is located on top of the auto box and underneath the inter cooler. And will have to be carefully taken apart to check the connections. O2/lambda sensors are a known failure on all Daihatsu models. Worth replacing both. Coil packs will break down in time again something to look to replace. A long shot is the MAP sensor. May have become faulty. Turbo overboost maybe causing fuel cut, this will happen when you fit a free flowing exhaust. Worth fitting a turbo gauge to check. Standard boost will hit 0.6 bar, car will handle up to 0.8 bar before ecu will initiate fuel cut. Hopefully that's enough to get you started on fault finding. Ideally if you do have something going wrong then the engine fault light will be showing, that's if no one has disconnected the bulb? Worth getting a scan gauge-II or similar and plugging into the ODB-II port to check for fault codes. Good luck from a fomer YRV Turbo owner!