Hey,
I know everyone will probably recommend ultrasonic cleaning (I have done a search thru the forum).

I am planning to just follow some DIY cleaning instructions I have found on the net, I'm not trying to restore to factory condition, just trying to stop it blowing soot on hard acceleration and idling poorly. (They seem to be leaking, I assume due to clogging preventing them closing properly, even causing slight issues when running on LPG)

My question is: Do I need to replace any O-rings on the injectors when I put them back, or can I just put them back on as is? If I do, where can I get the replacements?

Thanks (4cyl TS btw)

You are better off getting them pressure tested to see if any do leak, and chuck out those that do.
Can't really get to the needle and seat in a DIY attempt.
Reuse the "O" rings if they are still intact.

http://oldfuelinjection.com/images/injector02.gif

Could you pull them out one at a time, hook it up out of the manifold and turn on the ignition (don't try to start), and see if it dribbles? Just an idea, don't know if this would be safe to do or not seeing I haven't tried it.

<< Waits for flame attack.>>

OR - here's a better idea - with the engine cold, turn on the ignition, wait 10 minutes, turn off the ignition and pull the injectors. Look for "wet" ones. If one is leaking the pintle cap will have fuel on it.

<< Puts on flame suit >>