88 accord running rough

I have an '88 Accord LX (carb) with about 184,000 miles on it. A few
months ago it started to run rough, as in it has a rough idle when at
a stoplight, and when going down the freeway about 60 mph, it starts
to "buck" or "stutter."

So I gave it a tune up when this all started to happen (plugs, wires,
cap & rotor, pcv valce, fuel filters, o2 sensor, etc.) and that didn't
really do it. I let it go but now because its starting to bother me. I
thought maybe that it was the fuel pump. I checked the fuel pressure
with a guage today and it was at 1.9 psi, where it is supposed to be
between 2.6 - 3.3. So I replaced it and the psi is now 3.0. However,
this didn't solve my problem.

The rough idle occurs when the car is cold and hot, and the sputting
down the freeway starts at about 55 mph. When I accelerate there is no
problem its just when I am cruising. Any help would be great!

Thanks

 

Do a compression test and cylinder blow down test.