Does a 6 cylinder engine have problems driving uphill?

There's a little more to it than that... gap between gears, power-to-weight ratio, and overall drive ratio of the transmission, rear end gears, and tire revolutions per mile all factor into it. Plus there's the engine itself... when you say six cylinders, you could be talking about an old Ford 3.0, or a semi truck engine (they use an inline six engine, typically displacing 13 to 16 liters).