Engine sluggish in morning - need octane upgrade? on 2005 Audi A4 Quattro

The dealership checked and said everything is firing ok in the engine. But, the first 10 minutes are sluggish in the morning. Someone suggested that the Quattro needs the highest octane level of gas, could this be the problem? (I'm using the cheapest grade)

Asked by for the 2005 Audi A4 Quattro
Audi certainly recommends using at least 91 octane gasoline in their engines, as they are high performance. You car, however, will operate perfectly on 87 octane and what you would most likely experience is some horsepower loss.

RepairPal has some additional information on the trade-offs:

The best thing to do is to switch to 91 octane and test whether you experience a difference.
some guy is right to recommend a fuel system cleaner. I'd just add that 87 octane isn't necessarily cheap gas--87 octane from Chevron or Shell will have all of the detergents and optimal blends, same as the 91 octane from the same pump. But cheaper gas from off-brand stations can definitely cause exactly what he says.
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cheap gas usually does not contain much detergent and may have too much ethanol. both can cause power loss due to mixture and deposit problems. do not use dry gas (more ethanol) but do use some type of fuel system cleaner (techron or the stuff audi sells).