Ongoing starting issues, finally pulled code 7 91 300TE 4M

[puchscooter]

Hello all, first post over here. Have been having worsening starting issues for about a month now, ever since a long trip in the hot weather.

History:
Was doing about 80 to pass someone in my 91 300TE 4Matic, 206K miles, smoke silver with brazil brown tex, when I slowed down I saw some smoke coming from the rear end...went right away after 5 seconds or so, but I pulled it over, checked oil level and it was fine. Started right back up and I continued another 100 miles. Stopped at a rest stop for my baby to have something to eat, sat for about 45 minutes to an hour, and the car started right up, but was a touch hesitant for the first run up to speed (shuddering, felt like too much gas). Made it the remaining 150 miles home with no issues at highway speed, a/c blowing etc. Then starting it to go to work the next morning it was still acting up, doing the same thing (luckily only a 5 mile commute in). A few days pass and I am coming home from work and it starts dying at stoplights when I go to accelerate, but starts right up again and moves off. Now it is to the point where it wont even start but once in a while - like one time every other night I am out messing with it. When it does start it starts and sounds strong, until I leave it at idle and it conks out, or I press the gas and it conks out.

Things I have done to the car since the problem cropped up

checked cap and rotor, fine, cleaned a little bit of carbon out of there, but nothing terminal

plugs - nice and tan, spark seems white hot and constant

fuel filter - replaced because I couldnt find a record of it being changed, fuel regulator seems to hold a vacuum fine, pump is working fine, not too old either

cylinder head is within 30-40K miles of being rebuilt

OVP - checked - new 2 fuse style, replaced within 20K miles

tested throttle position switch - good open/close signal

getting 13.6 V system voltage

fuel/air adjustment - went out to sears and got a duty cycle multimeter, car only seems to run at 90-98% duty cycle when warm, though on warm up it runs fine and reads 50%. Did the static tests on it 2 times, one time everything seemed fine, push down the air plate, DC drops to 10%, full throttle drops the DC to 20%. Tried to repeat this after a few weeks, deflecting the air plate gives no change in duty cycle, when I actuate the throttle the duty cycle climbs from 70% to 90% mid throttle range, then drops to 80% at WOT. Additionally it is getting fuel through the distributor, if I lean it out the plugs dont get wet, if I richen it plugs are wet

So after this duty cycle test, I decide to pull codes even though the check engine light isnt on, and all I got was a 7 code. "TNA (engine RPM sensor)" is what I read the code represents. So I assume this is either the crank or the cam sensor. Wires look fine to both, but who knows about the internal condition in the insulation. Anyone know if the code represents one or the other, and if I can test the sensors? Also would a missing signal from either cause these issues? Any and all help is appreciated