My 5 Year old aussi

Question
I adopted my 5 year old Australian shepherd two years ago from the humane society.  He came with an assortment of problems many of which have calmed down in the past two years.  But he has a couple of problem that I just cant seem to train out of him
1.  When we go walking or running he goes crazy over bikers, runners, and sometimes cars.
2.  When we are on walks I let him meet one or two other dogs.  When we pass a dog that I don't let him meet he lungs, barks, and growls at them.
3.  He has always been a bit skittish.  He has a really hard time meeting new people (especially males).  He aggressively barks at them and though he hasn't bitten anyone I think he may someday.
4.  He has been in several dog fights.  He has attacked other dogs when there is food or toys around.

If you have any suggestions that would wonderful.  I love my dog but he is quit a challenge.

Ali

Answer
The first thing I would work on is his behavior on leash.  There's a really good book called "Click to Calm" which was written for dogs that are aggressive about other dogs, but the same techniques can help "reactive" dogs to focus on their handlers better, too.  
Many Aussies are reserved with strangers, and if not extremely well socialized as youngsters (that means during puppy hood) they may always be.  That doesn't mean that you cannot improve obedience to the point that you can control his movements.  After all, shepherds often need their herding dogs to stay still or move in different directions, so Aussies can be taught to do that.  I like to use clicker training because it's gentle, but effective.  If you can find a clicker trainer, great, but if not, there are some free lessons at www.clickerlessons.com.  The toy/food issue between dogs is unlikely to resolve, so that's a management issue - simply do not allow him in the company of other dogs when there are toys or food in the area (and use the free lessons to teach him to "leave it").  Also, if he has not already been neutered, you may want to consider it, as it can reduce aggression somewhat in some dogs.  If he guards food against humans, you may want to consider getting Jean Donaldson's book "Mine! A Guide to Resource Guarding in Dogs" and do the training protocols she suggests.