I am getting a heavy surging idle between about 1400 and 1600 rpm. I have adjusted the TPS and I am unsure of where to continue. Should i be pulling the throttle body apart to see what the plates look like? Propane testing?

And in what order should one play with the TPS, Air Fuel Mix, and Idle speed?

 

start with the simpler things before pulling the thing apart. start looking for vacuum leaks.

 

Had same problem and was narrowed down to a few things.
1. Vacuum Leak
2. Idle Screw
3. TPS

Do what I did. Remove brake booster hose. Buy a cheap cigar, puff on it and blow into brake booster. It should eventually come out the front where the intake would suck air in. If it comes from anywhere near the upper intake manifold you probably have a leak.

Be prepared for a monster of a f**king job if you need to replace vacuum hoses. Go really slow and take pictures and you will get it done. Took me about 5 days but if I did it again I could probably do it all in a single day.

Check your throttle cable for correct tension as well as the idle adjustment screws. Sometimes the idle control valve can get stuck by air filter debris and cause this kind of problem from what I've been told.

Good luck!