A bit long winded but may be worth a read if you have a similar problem. But firstly I will say the knowledge on this website was a BIG help so many thanks to you all and I hope my experiences will help someone else.
I drive a 2001 Astra 1.6 16v with the basic derestricted airbox mod.
Initially the car was occasionally hagging/kangarooing and occasionally cutting out at road ends but she started again easily and no EML light was showing so I spent an evening on google & on AOC looking for similar problems and all pointed to the coil pack, EGR valve or coked up throttle body etc. I spent the following few evenings cleaning the throttle body & breather pipes and blanking off the EGR but she still cut out and kangarooed randomly. So that Friday I took the day off work and parked outside a scrappie and tried different bits: I tried 2 coil packs and another throttle body but she still cut out and kangarooed. As I'm not a mechanic I was stumped so I borrowed a mates cheap fault code reader which showed no faults - humph - no faults but still an unreliable car. I decided to try changing the fuel filter as it was probably due one and the cutting out could be due to fuel starvation - no luck so I decided to bite the bullet & go to an ex vauxhall mechanic (Vauxhall were looking £70 plus vat to read the codes!!!) who had the official tech2 machine,(and he diagnosed it for free as I was referred by a friend) it showed my crank sensor & coolant temp sensor were faulty so I changed the crank sensor and the cts (the cts turned out to be faulty - reading 90degrees at startup) so I ordered one from vauxhall, double the price (£14) but the quality difference was amazing. Anyway the car went well for about 1.5 weeks but she still didn't feel 100% then finally the other day she kangarooed again and cut out but this time the engine symbol lit up....yippee a fault has finally appeared....which I diagnosed myself using the pedals!!
See this post by Geordiebandit - http://www.astraownersclub.com/vb/sh...78&postcount=2
So I self diagnosed using the above method and came up with code 0303 - misfire cylinder 3??? sounds like a coil pack fault or a plug fault - strange! so I went to another mechanic for advice who plugged the car in and read the codes for £10! which I gladly paid - it confirmed code P0303 so Geordiebandits code reading method really works - I'll admit i was sceptical. So I bought a coil pack for about £60 (not OEM obviously) and changed the plugs so fingers crossed my fault has finally been sorted hopefully.
Again many thanks to the forum posters in AOC who certainly guided me in the right direction and so far I have only paid about £140 for parts and 1 code read instead of £???? for possible solutions via the dealers. I hope my experience will help others and fingers crossed my problem is sorted.
The benefit of all this now is I know 2 good mechanics so when I need the timing belt kit, aux belt & water pump done this year I know where to go.