hi there. i've got a 97 Astra Estate with X14XE engine. been having engine power problems and temp. problems over the past few weeks. last thursday was driving along (slowly bec. of low power and temp wast at 100C range) when the car suddenly jerked forwared, engine check light came on but the car started to drive normally again with good power and temp. went down to 90-905C range which is normal. after i parked and turned off engine, had a smoke then started engine again, low power and high temp problem was back but engine check light stayed on. had to tow the car to the shop. any ideas?