Hello aquaman, thanks for joining the conversation. The 97 is slightly different than your 95. I do appreciate your input.sorry for any typos, i'm dealing w recent elbow surgery here...
if you feel this is ignition-related, please check the distributor. i'm not sure if this applies to GEMS ignitions, but this was also a mysterious issue in my 95 nas d90 because....
the rotor sticks onto the distributor shaft. when one removes the rotor by pulling up, and it sticks, it damages the clip on the bottom of the distributor shaft. hence, at about 1200 or 1500 or 1800 rpm, the timing is changing as the distributor shaft now moves inapprpriately up and down as it should not be allowed to move.
if this is the case, the fix is to replace the dist shaft clip (on bottom) or dist shaft as well. you will see too much up and down play on the distributor shaft. check this by temporarily installing a known good distributor
i now use channel locks to fracture and break apart the rotor before i take it off the shaft vs pulling on the vulnerable dist shaft and clip via the rotor
use anti-seize on the female mount of the new rotor also