My car I was given, I've had for a few months but just in the garage is a 98 EL Falcon Gli Dual Fuel, I got a Unreg Vehicle Permit so I could get it in shape for registration and all, anyway as I was driving it today I noticed when at the lights that it was idling really low (about 750rpm) it's a dual fuel but only runs gas (i'm not sure why) is this low idle ok, should I be concerned?
Also the steering is responsive but there is a bit of looseness about 1.5cm each direction of the wheel where it moves but doesn't turn the car? What is going on and is it a problem?

750 is fine if it is in gear - i'm assuming it's an automatic

As TwistedEL said mate, idle sounds fine if it's in gear.

As for the loose steering it could be a steering rack or links or bushes etc. Nothing major, but may not pass RWC.

Only running gas might be a problem tho unless your valves and several other components have been replaced

OK, so what about my EF idling at 500-600 in neutral? (auto)

Ah yeah, that sounds more like it, it's actually just over 600 like the guy aboves EF. Sorry for being a little vague and rounding up, it's an auto too and runs only gas but has petrol that doesn't work, Could it just be the way it's tuned for gas?

Idle speed sounds fine, as for not running on petrol you may find it's because the injectors are clagged a common problem with LPG/petrol engines when they are not run regularly on petrol. Read elsewhere that in the EF/EL's that regular injector cleans are common.

As for running straight gas wouldn't worry about it to much, it might be worth your while getting a LPG tickford GLI computer which will improve performance and economy.

I'd query the myth of having to change lots of things when running straight gas. My ZL has run straight gas since rebuild 80K so far and it's like new.

steering slack could would more than likely be rack ends if its excessive, but what you you have sounds fine, its more than likely tyre wall flex you are feeling not a rack prob.