Audi A3 losing power on motorway

[AngieT]

My Audi is losing power in 5th and 6th gear. The coil warning light comes on. I stop and start my car then the light goes off and I have full power. Taken to two different mechanics but nothing showed on diagnostic machines. Help!

[jsims1]

Could be a completely different fault but just had a golf 2.0 tdi come in at work with a similar issue, it was the EGR valve that needed replacing.