Strange Engine Noise on Highway

[Bearkat]

While driving on the highway the other day I noticed the engine had a "lawn-mower" noise to it which increased and decreased with the rpms. I thought maybe an exhaust leak, but it went away soon after I got into town. So I thought then it could be a miss in one of the cylinders. So I cahnged the plugs and wires, which made it better at the moment. Then, I was back on the highway today and it started doing that again just for a little bit. What could it be? Also, when it starts to make that noise, my performance drops a little bit and the muffler noise itself changes.

[3.4 slow to go]

what speed/rpm does it start/stop at?

[Bearkat]

Originally posted by 3.4 slow to go:
what speed/rpm does it start/stop at?

When it makes the noise it's at any rpm.

[cam98aro]

we need more of an explanation than it sounds like a lawnmower.

untill we get this we really cant help you.

[Bearkat]

Originally posted by victimizati0n:
we need more of an explanation than it sounds like a lawnmower.

untill we get this we really cant help you.

It happens randomly on the highway after about 15 mins of driving... lawnmower sound coming from engine... not the exhaust ad it's through the whole rpm range. When it happens there is a slight power loss and the exhaust note itself changes. It's not a miss, cause I changed the plugs and wires already. Sorry, but I thought I was pretty clear on my first two posts. :rolleyes: