The foamy you describe doesn't sound like a model that won't slow down. But it does sound like it's got a motor/prop that won't let it.
It sounds like a foamy with an major excess of power and an extreme amount of prop pitch. That much prop pitch on such a light model with the power to fly straight up without slowing isn't about to slow down unless the prop isn't spinning at all.
Turn the power off completely at say 100' and see how long it takes to slow down. Look at how long it glides in that time. Then fly your next landing with those two in mind. A two pound foamy with that size wing isn't going to hold it's airspeed for long. Unless it's got an 8" pitch pulling it along, and that much pitch on that powerful a motor will pull it along.
That plane doesn't need side slipping, it needs less pull from that motor/prop. Lots of speed prop planes have the same problem. It's worse for them as their airframes are a low drag as possible. The AWot's isn't.