Thanks everyone I really appreciate everyones comments, I have ordered some new sockets and other tools so that I can check all the suggestions so far.
ECU and throttle resets, this has been done everytime anything was changed and at least half a dozen times by me.
apparently this is a fault that only exsists on the very early 156's, it is an ecu fault. I have been told by an tuning company that my 98 156 has the prototype ecu it cannot be alterd only a new one at the cost of £560 quid will cure your problem.Slackening the throttle cable helped mine,if you do find a cure let me know.
I have seen the threads regarding the early 156's. I went to see my local (main) dealer who do not know about the ECU updates. My fear with the ECU is spending over £600 inc fitting on a chance it might work. I have seen reconditioned one on Eper for about £300 but I need to find out if these would include the updated firmware.
By sheer coincidence, I was thinking last night about the first time I used Alfadiag. I was having a lot of connection problems but the second time I gained access there was an error code stored which I did not clear and nothing was ever reported again. I now wonder if the reason why there are no errors recorded is due to a faulty memory or maybe I am just desperate and looking to deeply at the problem.
I spoke to EB Spares about the problem and they suggested a minor airleak could cause similar problems but the difficulty would be looking for a tiny hole which could be anywhere. The engine passed the emission MOT test
I have also ordered a new oil vapour valve (£2.50ish) as the idle quality is reducing. On startup, the idle fluctuates between 400-1500 for about 15 seconds before stabilising. Reading other threads there does seem to be a similar set of problems which are associated with the Lambda sensor, which were changed due to educated guesswork and because they would occasionally flatline and startworking again. But on the other hand what are the chances of having 3 faulty sensors.
When I was made redundant I lost my laptop so I cannot check anything with Alfadiag for the moment.