That ground wire that is on the firewall, should be bolted to the head. My 89 has a hook on the drivers side of the engine near the firewall. Just unbolt the hook and put the ground wire between the hook and the bolt.
Do you have a volt/ohm meter? If not, you can buy a cheap one for about $10 and then you can check the TPS setting.
Have you done a compression check on the engine?
The idea of getting it to run so rich that it blows black smoke is a little concerning since an over rich condition for a long period of time will ruin your O2 sensor, not to mention that it can wash your cylinder walls down and cause a lot of cylinder wear.
If you could get those pictures posted like 79coyotefrg asked for that would also help. Make sure the piston is at TDC. The easiest way to do that is, turn the engine over with a ratchet and 19mm socket with all of the plugs removed and use a small screwdriver or a chopstick or something small that will fit into the spark plug hole of #1 cylinder as you come up on the compression stroke. When you feel the piston touch the stick or whatever you use, slowly, turn the engine over and when the piston stops moving, snap a picture of the pulley and cam gear. Also make sure that both rockers on #1 cylinder are loose.
Take care.
Ken
