2015 Buick Regal

ON 10/10/2018 AT 6:45 AM, 63 DEGREES FAHRENHEIT, CERTIFIED/CURRENT LPT WARRANTY/15' REGAL PREM 2/ 60,600 OD 2.0L/TURBO/AUTOMATIC TRANS, CONDITIONS-SPEED-10 MPH-STEERING STRAIGHT, BRAKE AT 100%, ENGINE PERFORMANCE ISSUES MANIFESTED DURING THE END PORTION OF THE TRIP WHILE IN DRIVE, AT IDLE, DROPPING OFF FRIEND AT HIS WORKPLACE PARKING LOT. TRIP CHARACTERISTICS-TOTAL TRIP 35 MIN AT 20 TOTAL MILES-FIRST PART OF THE TRIP AT 45 MPH FOR 15 MIN/THE MIDDLE PART OF THE TRIP AT 70 MPH FOR 12 MIN/END PORTION OF THE TRIP AT 15-25 MPH FOR 6 MIN/IDLE AT 2 MIN-ENGINE PERFORMANCE-SUDDEN ONSET OF HIGH, ROUGH IDLE OR ENGINE HESITATION? CHARACTERISTICS SEEMED TO INCLUDE INCONSISTENT ENGINE PERFORMANCE SOUND AND FEEL FELT THROUGH THE PEDALS, THE DRIVER'S SEAT AND STEERING WHEEL, BRAKE PEDAL DEPRESSED AT 100%, IMMEDIATELY AFTER MOVING THE AUTOMATIC TRANSMISSION KNOB FROM PARK TO DRIVE, ENGINE TEMP WITHIN NORMAL PARAMETERS, GAS LEVEL 35 MILES TILL E. IN DRIVE, ACCELERATOR AT 15-20%, DROVE 35 MPH FOR 5 MILES TO A SHELL GAS PUMP, SHIFTED TO PARK, BRAKE DEPRESSED AT 100%, DEPRESSED ON/OFF ENGINE BUTTON, ENGAGED THE ELECTRONIC PARKING SYSTEM, MAX FUELED VEHICLE WITH HIGH-GRADE UNLEADED FUEL. VEHICLE SAT, UNSTARTED, FOR 15 MIN AFTER FUELING. DROVE TO THE AUTOZONE ACROSS THE STREET, 1 MILE/20 MP, EXPERIENCED A MIL COMING ON SOLID IN THE IP WHILE PARKING THE VEHICLE. OBTAINED MIL PRINTOUT READ: "CYLINDER 4 MISFIRE DETECTED"/"ASE CERTIFIED MASTER TECHNICIANS HAVE SEEN THIS ISSUE ON YOUR TYPE OF VEHICLE AND THE MOST LIKELY SOLUTION IS: PERFORM ENGINE DE-CARBON PROCEDURE"/CODE P0304. AT PRESENT: ON START-SOLID MIL, ROUGH, HIGH IDLE AT 1500 RPMS, AFTER 1-2 MIN-MIL,TCS SOLID, ROUGH IDLE AT 1000 RPMS. DRIVABILITY AT ALL SPEEDS AFFECTED BUT LESS SO AT HIGHER SPEEDS, *SIGNIFICANT LURCH AT 15-35 MPH FEELS LIKE HARD SHIFT/INTERMITTENT. I CHANGED OIL/AIR FILTERS, DRIVEN 2 MILES SINCE PARKING AT RESIDENCE.