It doesn't happen if I put the truck on park and press the gas from idle to 2000 rpm (or higher although I haven't tried higher). However while driving, it starts sort of charping from 1st gear and then hissing rest of the time. My guess is the hissing noise is coming from trh cat? It seems like both the charping and hissing coming from the front passenger side, well that's what my wife said while she was sitting on the passenger side. Form the driver sit it feels like it is coming from under the passenger side to me. It's really hard to pin point where exactly it is coming from. Is this some sort of leak? Any one else had it?
Thanks
Thanks