Hey all, I'm after some advice about my EF, it has s problem with running on petrol, gas runs excellent but I have a unstable idle, random engine speed increases when taken out of gear, and a fuel smell out of the exhaust, the unstable idle is that it will randomly rev up to about 1300-1500 RPM and then settles back to about 800 RPM, and I have had to stomp on the brakes occasionally to stop it from surging forward as I slow down in gear, and revs up to about 2500 RPM when taken out of gear, then after about 10-15 seconds it comes back to idle, I used a scan tool and it has the following codes
411 can't control low idle,
412 can't control high idle
511 unknown EEC-V failure
521power steering switch

I have replaced the ISC,cleaned out to throttle body,new can any sensor, temp sender, replaced the fuel pressure regulator, cleaned and service injectors, new pump and filter, new inlet manifold gasket, new plugs and leads and swapped out the ECU for a similar one.
Any advice is much appreciated