Oh Snarktastic One:
I am firing my agent and beginning the query process all over again. Ugh. I am worried that my Lazy Old Agent won’t remove my name from the agency website right away. If I’m Googled by any potential agents, this could create a problem for me. Do I mention that I’ve recently left another agency in my query letter? Also, I made many revisions to my manuscript for LOA. Should I submit it as it stands now or re-revise it back to where I had it before? I now question LOA’s judgement. But never yours.
You don't need to worry about your name turning up on the previous agent's website because you will say "my former agent and I came to a mutual parting of ways" at the close of your query. What other agents are going to want to know is whether this ms was shopped around. If it was, you're going to have to deal with the fallout from that (ie it's going to be hard to find a new agent for it). If s/he did not shop it, you mention that too: "my agent and I have had an amicable parting of ways before s/he began shopping this ms".
You have amicable partings even if firearms were mentioned or brandished. "I fired my lazy ass good for nothing sorry excuse for an agent" may indeed be the Dog's Honest Truth but it's not a persuasive sales point in your query letter. I have five clients that were formerly represented elsewhere and they were all very very polite in the initial query letter. Of course, I pried into the actual facts soon thereafter but that involved copious quantities of gin and blood oaths of secrecy.
I have no idea about the revisions part of the question, nor would you want me to comment on something I haven't read.