TS rough running update-coil packs?

Hi all, thanks for all of the responses to my last thread regarding my poorly 166 TS. After spending £350 having the fault NOT identified, I have had to take it offf the road and go back to driving a Passat. On the basis I now don't trust even the supposedly more competant specialists to diagnose the fault I am going to try the elimination method. AS the running has got worse, appearing as loud/raspy exhaust note, vibration through the rev range (even when stationary) and all worse under pressure, ie hill climbing, hard acceleration, I am begining to think ignition related. Nothing showed up on Examiner, but is there any way of testing the coil packs (apart from replacement), are there any other parts of the ignition circuit that are known to fail apart from coil packs (and obviously plugs), what else should I look for. Any experience or comment welcome on this. If I find it's not the coil packs or plugs what next??????????