Loss of power at high angle of attack

I just took my first flight lesson in the Coupe. We tried to do stalls at full power but when we at a higher angle of attack, about 80 mph the engine began to lose power....Leveled it off and ran normally. This is a bit of a concern, what if it happens on take off? What could cause this? C75, auto gas, no ethanol, 91 octane. First time in the air for the aircraft in 12 years. There were also rumors about this happening before in this aircraft. Otherwise it was great, ran fine, 120 mph at 2300 rpm level flight. Oll temp ran at 210 degrees, 30psi.