Well lads. After changing the fuel filter in my 90 efi it greatly helped the acceleration in the car. I thought it was near enough back to its best but when the revs get to around 3500-4000 rpm it gets like a small hesitation and then continues to rev. Im not overly confident overtaking in it at the minute. Any suggestions as to what this could be. All I'm thinking right now is that some dirt could have gotten into the injectors maybe as the fuel filter was pretty manky to say the least. Thanks!

 

Try some injector cleaner to see if that helps!

If not you may have too take the inlet off and change/clean the injectors