Engine output limited when PDC activated

[snapdragon]

Here's a connundrum.
Yesterday, I was on my drive trying to drive up ramps and the car wouldn't produce enough power to get up them even with my foot right to the floor. I tried three times and the rpm was limited and pressing the accelerator more than say 1/4 had no additional effect. The parking sensors were beeping due to the wheelie bin, so I moved the bin and the car went up easily. Do you think this is an intended feature or a fluke?