1898 Accord exi help needed
 

I have a 1989 honda accord exi. Has the 2.0 4 speed in it. Thing is that
the car runs awesome till it reaches warm or 1/4 temp on the dash temp gauge
, then it idles rough. I assume it is the coolant temperature sensor, but am
new to Honda's.. ALSO the tranny shifts hard.. every gear shifts like the
thing has a shift kit.. I put some lucas in it and it helped a bit..but was
wondering if there is any parts that are known to go like a vacuum modulator
or something ... ANY help woud be great.. thanx