I'm guessing you may have multiple problems and by fiddling around in trial and error mode you may have made some things worse, like idle speed. It's a rooky mistake we often make, you'll quickly learn.

1) Kickdown cable does not affect engine operation, just shifting, but will noticeably affect driveability and engine load until you get up to road speed. Once you get the engine running properly you will need to address that. Bit of a PITA job, but quite DIY doable, do some google searching, but everything you need to know should be in the 700/900 FAQ here. Remember, your engine and trans are exactly the same as that used in the 740 models of your vintage, so there's a ton of stuff in the FAQ that applies to your car.

2) You need to be sure you have a properly functioning AMM before carrying on. Simplest thing to do is try swapping in a known good working AMM (like from a friend) or better yet in your situation would be trying your AMMs in a known working LH2.2 car. AMMs need to be tested out at both idle and higher rpms as well as response during engine acceleration. There are formal testing and adjustment methods in the FAQ if you want to confirm the diagnosis (at your level, probably best not to attempt adjustment, I don't even do that, easier to just swap). As a bit of an aside here for your added edification, if pulling the AMM connector (puts the ECU into what's called limp home mode) ever makes things start and run any better (albeit with rough idle and weak acceleration) then you would definitely have a failed AMM -thinking of that, be sure to disconnect the pre-heat hose from the exhaust manifold shield (or alternatively screw the internal air box flap shut if you have to undergo vehicle inspection) to prevent frying the AMM if the air box thermostat should fail (which they periodically do).

3) Make sure the whole throttle and idle setup is clean and properly adjusted. Most especially the throttle plate, the center area of the throat and the two tiny vacuum ports (also check the associated vacuum hoses and check/clean your flame trap). When using the air bypass knob to adjust base idle, you need to force the idle air control valve (IAC) to stay closed. There's an open connector on the fender wall you jumper to ground to disable the IAC. Related to that, when you first aquire a car, you should check and adjust both the throttle spindle linkage rod and the idle sense switch, which as I recall for your car is a microswitch sitting out in the open (kickdown cable adjustment is normally done at the same time). Again, a good place to start reading is here in the 700/900 FAQ Setting Base Idle Specs and Mixture on Bosch LH2.2-Equipped Cars. I highly recommend you start by removing both the throttle body and IAC to the bench for a thorough cleaning and properly set the throttle plate stop position (again, see FAQ). As an aside, once everything is clean and properly set, if the idle is ever erratic or stays a bit high during warmup, then it's quite possible you have a sticky (worn) IAC. If tapping on the IAC while running (like with a wood stick) causes the idle to change then that's the sign of a sticky IAC -could be deposits in the chamber with worn/dirty bushings, but most likely wear grooves are starting to form where the contacts ride on the armature, not at all uncommon in older LH2.1/LH2.2 spring loaded IACs (the LH2.4 floating IACs seem less susceptible to that). Although many recommend against it, for a really grungy IAC, I have no hesitation in soaking it in solvent, just keep the motor end up and out of the cleaner, shake it out and dry it thoroughly. And as for contact wear, until you can find a better uased one, rather than prying it open to try polishing out the grooves, my favorite temporary fix was to lower the base idle a bit to keep the contacts normally riding away from the notch that develops at the end of the grooves.

4) And finally, it really sounds like your ignition system may be giving you grief. First off the proper setting is like 10-12 degrees. If setting the timing at zero degrees is an improvement and the timing belt was recently changed then I'd say the odds are high (as in almost for sure) that the intermediate shaft was improperly aligned with the belt mark. Your mechanic may only have checked the cam pulley alignment in relation to the crank at 0 deg. He'd have to pull the crank pulley and lower timing cover to properly check everything, not exactly a 5 minute job. Additonally with your distributor and in order of likelihood, the distributor cap and rotor may be worn (if they haven't been replaced in living memory, time to do so), or you may have a failing Hall Effect sensor inside the distributor or the distributor shaft may be badly worn. On my old 1985 240 DL, I had a mystery hard starting and startup rough running condition that I couldn't figure out which eventually turned out to be a worn distributor shaft. And finally, make sure you've got good plugs and ignition wires, again maybe time to treat you car to new wiring if they haven't been replaced in recent years.

Good luck. I've loaded this reply with lots of extra tips for future reference. Keep at it, you will eventually get it running right and will learn a lot in the process -all very satisfying, at least for me.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now