Transmission problem?

[Chris1991]

Hi my vz v6 Calais when doing around 80-100km if I back off and then accelerate lightly again the revs will actually drop below 1500, and I will get a slight shutter it seems from my front wheel and just feels real sluggish. I have to really give it a bit to get the revs up over 2000. Was just wondering if anyone can help or has had a similar problem. I've taken it to 2 mechanics and an auto electrician, and they don't seem to know. Cheers guys.