Rpm will fluctuate between 1500 and 200 in park and drive (not reverse) will stall and unable to start again for approximately 5 mins. Check engine light is not on and no codes appear. I've replaced maf sensor, cleaned throttle body and valve, and used fuel cleaner. The fuel cleaner help for about 1 full tank gas and then problems were the same as before. Should I replace fuel pressure regulator next or something that's a lil cheaper first???