My Renault Megane has recently started to play up. Starts pretty ok but all revs go up and stay around 1000/1100 when before it used to be 600/min. Than happens right after the start and stays for few more minutes while driving. Then the revs drop to normal (600). Sometimes when driving the little light pops up on the dashbord (RHS-orange colour) indicating a problem with the ignition. Happens usually when the car is warm. Few weeks ago had a problem with the revs going down and the car kangarooring (especially on 1st and 2nd gear). Changed spark plugs but that did not help. Now thinking of changing ignition coil(s) as this could be the cause. Anything like this happened to you? Thanks for advice

Hey, if the orange light your talking about looks like a squigly line, which is the electrical light, a safe guess would be either the pedal potentiometer or the throttle body its self.
Get a dealership to print out what the faults are, as when a light comes on it will log information about the problem on the vehicles computers.

Renaults coils are a very common problem, esp with your syptoms. Good bet is to change them. You may only need one repalced though. So i'd unscrew the coils from the head and slowly pull up one at a time. The one (or two) which make little difference to running of the engine need to be replaced.