AUDI A4 HESITATION UPDATE?

SO BEEN HAVING AN HESITATION PROBLEM ON MY 1998 AUDI A4 1.8 20V NON TURBO AND IT SEEMS TO HESITATE ALWAYS AROUND 2000RPM THEN WHEN IT STRUGGLES PAST THERE ...BANG THE POWERS THERE EVERYTHINGS GREAT IVE NO EML LIGHT ..BEEN GARAGE NO CODES STORED GARAGE TOLD ME MIGHT BE COIL PACK BE CANT BE SURE IVE PUT NEW PLUGS IN MADE NO DIFFERENCE..CAR IDLES FINE NOTICED NOW AND THEN WHEN STARTING THE CAR CAN BE HARD TO START IT WILL START UP BUT IDLE AT NEARLY 0 UNTILL I PRESS THE THROTTLE THEN IT WILL SETTLE BUT LIKE I SAY THATS JUST THE ODD TIME NOT SURE IF THIS IS CONNECTED TO THE PROBLEM ETC..IS THE TPS AN OPTION? WHERE IS IT LOCATED ETC ANY HELP IS ALWAYS APPRECIATED..IVE ALSO UNPLUGGED THE AIR FLOW SENSOR AND THE ENGINE SEEMS SHAKY ETC SO I GATHER THATS WORKING