Most people straighten it up, and the results in the ECU thinking it's off idle and add more fuel like a accellerator pump jet.. Also, chipped ECUs will run like crap too. There are too many floating around these days. Unlikely to be weak spark with 4 coils, unless all 4 are cooked. Check your earths and measure the 12V at the coils while engine is running. Could also be old and leaky injectors.