This just started happening to me. Was just driving regularly and the needle on my type r tach just started to move randomly up and down for alittle bit then go back to where it was. I have a VAFC hooked up too and that reads the rpm's ok, but not my type r tach. Also the engine dies out on me sometimes when its just idling. No check engine light or anything! I have no clue as to what it could be. Also the engine from time to time seems to hesitate or like misfire or something, cuz it kinda jumps or lunges iono how to explain it, but if anyone can help me out i would appreciate it.
Thanks,
Matt

 

just sounds like a fuel problem to me. that or a bad ground somewhere causing a sensor to read improperly. Its hard to tell though, this is the kinda thing you have to diagnose in person