I have through some somewhat similar problems as you describe. After trying replacement coils and one of the Lambdas everything was cured by replacing the TPS with one of the pattern parts linked to earlier by Santa. I could also smell exhaust, not everytime but enough to notice. There's a thread about it....http://www.ukgser.com/forums/showth...m-idle-balance-Erratic-idle-amp-rough-running
If you have or have access to a GS911 do study the outputs very carefully and get the sample rate as high as you can, also select just the item you want to examine in detail. By doing this I eventually spotted some very small fluctuations in the throttle angle but when I replaced the TPS the line was completely flat at tickover where before there was just the occasional ever so slight blip. For £38.50 and a few minutes to fit its got to be worth a go with a new TPS.
If you have or have access to a GS911 do study the outputs very carefully and get the sample rate as high as you can, also select just the item you want to examine in detail. By doing this I eventually spotted some very small fluctuations in the throttle angle but when I replaced the TPS the line was completely flat at tickover where before there was just the occasional ever so slight blip. For £38.50 and a few minutes to fit its got to be worth a go with a new TPS.