Chris,
For a 1G Talon, you've made all the necessary maintenance procedures that were probably due anyway; spark plugs and wires, fuel pump, air and fuel filter. It's possible the fuel injectors need replacing, but I'd hold off on that.

The good news is, mostly likely there is nothing wrong with your car. The “bad” news is that this is the norm for non-turbo DSM cars; especially the ones that have the 1.8L SOHC engine. It is under powered. When I've driven one of those models, I've had to drop it into 3rd going up steep hills myself. The non-turbo, 2.0L DOHC engines handle hills better, but still may loose a lot of power on those hills. The shaking is simply caused by your car getting too much fuel and not enough air for the gear ratio you're in, and not enough clutch. You'll probably experience the same thing if you try to start your moving from a dead stop in 3rd or 4th gear.

There are a couple things you can do to see if it helps. Use high octane gas; 93 octane. It seems more expensive when you look at the prices per gallon (or litres depending on what country you live in), but in the end, you may only be spending a couple more dollars for the same amount of gas.

If there is still something mechanical you feel is wrong with the car, you can have the wheel bearings and the torque converter checked out. If the wheel bearings are going bad, you'll probably be noticing a fair amount of noise coming from the wheels. You check if this noise is happening by putting the car in neutral when coasting down a hill. It'll sound kind of like a faint whining noise coming from your wheel(s). If your torque converter is going bad, that'll definitely cause lack of power. This can be much more expensive to fix than the wheel bearings or using high octane gasoline.

I'd suggest not putting any more money in the car for repairs just yet. Try the high octane gas first to see if you notice a difference. If that doesn't seem to help after 2 or 3 fill ups, inquire about the cost to have the wheel bearings replaced. Those parts aren't expensive, but it can be labor intensive. If all else fails, have your torque converter checked out. If it's determined that it's still good, leave it alone. You'll just have to accept the fact that 3rd gear is required when climbing those steep hills. And if you live in a high-altitude (moutainous) area, even the turbo models require down shifting to maintain speed going up hills. It's just physics and the laws of the universe working against you :)

Good luck!