How to Fight for a Raise You Deserve?

Guys I've been underpaid for way too long. I am a project manager for an environmental consulting firm and I have been with the company for 4 years. I know I am too qualified for this job given I have an engineering degree and an MBA (no one has a masters expect me). I've also been there the longest expect one person. I've been looking for a new job but I've been struggling to find a new one in this crazy market and possible pre recession. I know I am bringing a lot of value to this company, and I carry so much weight. I have to manage so many projects, supervisor, train, delegate work, communicate with clients, write proposals & bring in money. The end of a work day I can't talk because I'm drained. I know the other PMs are lazy because all the staff below us have told me the other PMs don't have expectations when it comes to deliverables, so basically they have been delivering low quality work to clients. Someone who got promoted 1 year in as a PM with 0 prior experience in the industry because he was going to quit and that was the only way they could justify his salary increase and they couldn't afford to lose people. He makes a couple thousand less than me when I've been there 4 years. But somehow as an entry level he makes the same as someone who's been there for 4 years. He's brought in 0 work. He has 0 clients. I don't think he brings any value to the company, he can't even manage his own projects and relies on me.