Loosen the exhaust pipe at the manifold flange. Air has to get out of the engine as well as getting in. I've seen deteriorated mufflers collapse inside, and some exhaust pipes were also made from one pipe nested inside another and the inner pipe can collapse and restrict the exhaust flow.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!