ID conflict?

Ok, I installed a other mod and the ID conflict started I tried to change the ID but after a hour I got really bored, so does anyone know how to fix this easy? Is there somehow you can see what ID are in use? I tried to install a "ID resolver mod" but that mod itself crashed minecraft (tried also with a new .jar file) or must I just keep enter a random number until it find a empty ID?

Also is the max Id you can have 255? after I go past that it give me a other kind of error.

I did re do every ID I could change starting from 140 and got to 202, but the I entered my word I got 5-9 FPS, so I tried to turn of all mods loggin save and start them again, it started fine, but as soon as I added solar panels I got that huge FPS drop again.

You got a clue on why, and if I could fix it? Going to start a new world tomorrow and see if my old world just wont work for a strange reason but I been fixing minecraft problems for like 3 hours so I give it a rest for now.