I was actually thinking of adjusting the shift linkage because I'm getting the OD shudders when in slower 4th gear speeds. Maybe this is another good reason to do it.
Very true, I definitely know how the ignition system works now ahah
Thanks for all the help, y'all!
Shift linkage != TV linkage
Shift linkage = I put the lever in D, and the trans is in D.
TV = I push the go pedal and the trans knows how far I pushed it.
If you have driveability issues that you believe are affected by TV pressure, such as staying in OD too long as you decelerate/shifting into OD too early, you would adjust the TV pressure. I'd suggest a new thread for that topic as needed, it could be any number of things (maybe it shifts right but you have a misfire in high load low rpm conditions).
89 and back cars have a metal rod in the engine bay against the firewall that is adjustable to set the accuracy of the shift lever. Don't touch this until/unless you're completely positive it's screwed up. There are also bushings on it (down kind of beside/behind the exhaust manifold) and if they are in rough shape you'd end up with a loss of accuracy in the shift lever (Park on the cluster might be "just barely out of Reverse").
There is also a breakage-prone plastic bracket piece on the steering column (inside, wrapped around the steering shaft, under the cluster) that is responsible for the position of the shift indicator needle in the cluster.
With the 90+ shift lever (it's 100% different) there are plastic bushings around the shift tube that wear out and cause excess slop and loss of accuracy. I'm not sure if the same can happen to the older ones or not, if so, it's yet another cause for the needle in the cluster to not match the physical placement of the shift lever which may also not match the actual position the transmission is in.
Your inability to start the car unless you push the lever all the way up firmly is either:
-the shifter linkage has slop/play/is out of adjustment (trans was not fully in park, was somewhere in between reverse and park) or
-the neutral safety switch is worn/inaccurate (trans was in park but neutral safety switch did not see that it was in park)
I'm not sure if the neutral safety switch is adjustable at all. If it is I'd start there even though it's annoying to get at.