Guys, had an "intresting" noise coming from the left hand side (drivers side) of the the engine yesterday I have never heard before. I left the pickup running to check the tranny fluid level and I noticed there was, as best I can describe, like an air leak sound. It wasn't an exhaust leak as I got up into the engine a little bit and it was definately sounding like it was coming up towards the top of the engine up by the intake/heads. Sounded almost exactally like a tire slowly losing air. Wasn't real loud, but you could hear it over the idleing engine. I couldn't hear it inside the cab. I was thinking vaccum leak, but isn't that primarily on carbeurated engines? I haven't noticed any loss in power, but my mileage lately seems to have dropped some. I felt around the engine and couldn't feel anything leaking. Strange. Any ideas?

Use some ether and spray around base of intake and surrounding sensors and if it spikes in RPM you found where its getting in.

Yes vacuum leaks are for any engine....thats essentially what an engine is..A big air pump.