Sick little Hachi

[cab32]

Hi all i am new to the website and have introduced myself in the newbie section...so hi to all,I bought in a JDM 1987 AE86 Toyota Corolla Coupe Levin it arrived friday,the car is in very good condition and has an AE92 engine fitted.

The mods are M's (k&n) factory induction kit,four branch manifold with decat pipe and full stainless system andTrd plug leads.Thats all i think that is done engine wise and i goes lke stink.On Tuesday after driving it for about two hours doing hard and slow driving it started to splutter as if it was misfiring also while doing this the engine check light and the catalyst over heat light came on at the same time( thought it might just have gotten to hot) .

Bought the car home and the next day i changed the plugs as old ones were bad.Put Denso plugs into it and it ran smoother,started it up and went driving.Again after two hours it started to do the same accept it was worse this time with the two dash lights mentioned above coming on and off more.Did the same thursday and friday,then today its now doing it from cold and the car just cuts out on idle and acts eratic when you try and drive it.Can anyone HELP

Thanks in advance.