Don't mess with the EHA valve. Do the dist cap and rotor first. Then, plugs (only copper, non-resistor)and spark plug wires (if not fairly new already). The EHA valve is probably ok. It's also a pretty expensive part ( like $350.00) and the adjustment is very easy to screw up and not be able to get back to starting point (I ended up buying a new one and it wasn't the issue...ouch). Report back after you do the above.