When you say your average HR is 176 are you referring to your average HR on hills?

I agree with the above poster that you need to ride hills to get better on them. Hills riding is the best test of your power/weight ratio there is. You can get away with being a bit weak on the flats if you're in a group, because you can just draft. Its not as useful to draft when you're going uphill.

So basically you need to increase your power and/or decrease your weight. There is plenty of information around on how to do that. Start putting some intensity into your training (riding up hills will do that) and make sure you are eating right and getting plenty of rest & recovery etc etc.

There is also a strategy to climbing hills when riding in a group if you aren't so strong... make sure you get to the front of the group when you hit the bottom of the hill. Then gradually fade to the back as they overtake you, while using the other riders as much as you can for drafting/pacing.