I'm hoping that someone can provide some insight. I have an '89 SE w/149,000 miles on it. I recently tuned it up after having it sit for some time. I replaced the the plugs with NGK OEM plugs about 6 months ago and I recently replaced the cap, rotor, wires, and PCV valve. However, I still have a problem with it running rough. It idles around 750 RPMs, but the Tach fluctuates and the car shakes telling me that there is some roughness. Not sure if this is related to a leak in the intake manifold. I checked the outer walls with a propane torch and didn't find anything. Is there a way to test the gasket for leaks on the inside without having to pull off the intake manifold? Any other ideas would be appreciated.

 

had similar issue on my gf's mazda that had a leak there - replacing the gasket fixed it

i think the mechanic sprayed carb cleaner around the area and watched/listened to the engine/tach. it was a while back, so I don't remember 100%

 

check out your exhust system for holes, mine had 3
dadadadadadadada

 

I should have mentioned this, but I didn't. I replaced everything but the exhaust manifold itself: muffler, catalytic converter, flex pipe. However, after I did that, the car still seemed to be a little louder than I remembered it being. Would this affect the idle?

 

it did for me

the louder the exhust the more shakes I get in the cab/car