about 8 months ago i bought my forst astra. its a sri with the z18xe engine.
when i first had it, it went like a rocket, it used to outrun audi's with similar engines. the only mod it had was a k and n open cone.
i changed the filter for a the standard air box setup with a courtenay panel filter and it didnt feel any different. i thought i was having heat soak from the cone filter. then i put a cat back exhaust on and it made a bit of a difference. then i had a full service - cam belt, water pump, oil filter oil and liquids. all still fine. well about 6 weeks the battery went so i hadto change that which also resets the ecu when the battery is disconnecting, then i started to have a loss of power. it seems really sluggish on acceleration until it hits 3500 rpm. iv cleaned all the pipes on the throttle body and changed the MAF meter. any ideas where iv lost the power, or is it just old age on the engine? the engines done 85k miles. im wondering if the car had a remap when i bought it and when i dosconeected the battery it somehow reset the fuel map to standard? its really strange.
any help will be useful to me as im a bit confuzzled about this!!