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at idle or at constant speed it sounds like a rotary.

like the idle timing is bouncing up and down...sounds exactly like a rotary.

also when next to another car or wall i can hear it like a hissing intake noise up and down in pitch.

any ideas?
idle timing?
throttle body or accell cable?
sparkplugs?

Checked for leaks in your intake? That will make a hiss and effect idle.

A leak at the exhaust gasket will also make a hiss and change the engine note.

yeh i checked the intake tubing and filter...its all tight and no holes, gaps...

will check exhaust tomorrow - could be because i have been getting wicked exhaust rattles lately. could just be the heatshielding but as per usual na6