ok my grandpas 87 civic runs and idles fine. you can basically floor it threw 1st and 2nd but at freeway speeds you have to baby the throttle because if you give it too much the car actually slows down. so what can be causing this. about 9 months ago i replaced the head gasket, cap and rotor, plugs and wires. if anybody can help please help .

 

Carb or efi?

from the easier to the more $

Pinch the egr hose

Which spark plugs, I had issues years ago when we installed some cross reference spark plugs it could not go over some steep hills.

 

it has a carb and a million vacuum lines. and im quite sure the plugs are ngk but i dont know the heat range. the car started doing this recently.

 

The carb has a million and half mile of hoses.

Start with the simple things

Replace both fuel filters, the rear one by the driver's side rear wheel and the one by the valve cover. The rear one can be a pain, the cross reference one from Fram that I got was not exactly the right size to fit in the bracket, I spent half an hour to hack the bracket. Check w honda if they still have the rear fuel filter.