Motor idles up n down in 500rpm blows black smoke and dies when u put in gear. How many airffliw sensors are I replaced the 2 bolt round one. What else could this be computer? Cat? Any suggestions on what to repair next

The IAC (intake air control) can cause this.Got a photo of what u replaced?
The TPS can cause issues, and the other is the Maf or mass airflow sensor.
Did u have the vehicle scanned for computer codes? Is the check engine light on?

What is the "2 bolt round one" you replaced? Was that the Idle Air Control? The would be the first thing I would look at. Next would be the throttle position sensor. Here is a write up on how to test it:

https://www.gmforum.com/trouble-shoo...sensor-279319/

Also, check for any vacuum leaks.

No codes were shown to last mechanic. He couldn't communicate with comp. He thought that was the issue. If I replace computer is it just plug n play or would it need programming

You'd have to get it programmed to your VIN, but there are some people who sell used PCM'*, and they can flash the VIN to it for you, then send it to you, from there it is pretty much plug and play.
I'm not sure it is the PCM though, is the mechanic using a scanner that can communicate with OBD 1.5?

i think 93 would just be obd1. they had the chips, but if you get a different pcm and put your chip in it that still could be the problem. i would go through the mentioned tests first, pcm is normally last resort and not a very common failure

You're right Justin, my mistake, it was 94' and not 93' when OBD 1.5 came out, that is what I get for posting after being up all night.