Car misfiring, engine light and drop of top speed

[matty_09]

hi all my engine light in my corsa started coming on usally when on the motorway at around 70mph it would come on and if i accelerated it wouldnt have any affect and car would just stay at 70mph
it got worse and started doing it in 3rd 4th and 5th gear engine light would come on and couldnt accelerate but if i let the speed drop and accelerated back up it would usally go fine. so i took exhaust i had on off and put the standard one back on and did the same with air filter. but now engine does come on at 60 to 70 and it wont go faster than 80mph.

can any 1 help??

[dandadan]

are you able to do the paperclip test?

[matty_09]

No its 1 litre

[rich3115]

same thing happened to my 1.2 its getting annoying