New here. Are the 04 Fe 450 any good?

Welcome! You're in the right place to find answers. The wiki is the best place to start learning about what's typically wrong. Also search for a link to owners, parts, and service manuals all free and stored offsite. From there, and from limited experience with my own 06 FE450e, I've gathered:

Reliability improved in 06 due to manufacturing moving to Austria. Bodywork was updated at that time. Other parts are mostly interchangeable. Check the wiki for which areas are less reliable in an 04.

I'm pretty sure I've run mine with the tps disconnected while troubleshooting an ignition problem. I don't remember it making any difference, but I didn't push it or ride it for long that way. If low idle is your only symptom, adjust the air mixture screw and idle before digging deeper. Check the shop manual for instructions.

I have really enjoyed mine. It's fun. And fits the budget. But parts aren't as easy to get as a brand that's still in existence. I use ktm-parts.com usually. They have the Husaberg parts manual available to look at right on their site, and you can easily search by part number.

Was yours a good deal? As long as nothing major is wrong and it was reasonably well kept, I would think so. Service intervals are short, but I don't mind working on it.