DFM

It's July. Not cold. Also looks like 37.3 is really close to that envelope. Quite a bit closer than a plummet to 33.5 that it had never been at. Also aircraft POH on takeoff calls normal between 36" and 38" on launch.

And of course as always......hind sight is completely 20/20!

Hi guys. I realize this is an old post. This is my first reply to one of these. I had a similar problem. Previously had 37.3" on the roll typically. After a long New England winter with several months of minimal flying, my MP on the roll was 33.5". The plane seemed to perform well otherwise but it certainly got my attention. I had several different mechanics look at it and come up with several different convoluted theories spending many thousands for useless the useless theories. On a day recently an 87 year old retired mechanic without even looking at the airplane said he'd bet it was a leaky intake manifold gasket. He was right. I'm back up to 37.3" on the roll.