Fuel ingection system?

Hi, I have a 2002 Dodge Dakota, has about 117000 miles on it, its 8 cylinder, Automatic. Now here is the deal, When I am driving it slips with the changes of gear, when I am Idle the RPM's are constantly changing. But when I actually press the brake to come to a stop it will stall out completely unless I am feeding it gas. I have figured out that something about pressing the brake is causing the ingection system to not feed it enough fuel, I have also asked a few people and they all say the same thing, which is it sounds like the ingection system is clogged. Every auto shop that I have contacted has told me that I should just change the pump, not only the filter. The parts and labor are about $400 dollars, I cant afford that. Is there any alternate advice someone can give me?