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You can check the timing, the computer timing control has to be grounded at the Dara connector. My bet is, it is something else on your CCC equipped car. Is the check engine light on? Vacuum lines must be in good shape. Good luck.
If it dies immediately after shifting into gear, and restarts normally in park or neutral, the converter clutch is probably stuck on. The valve in the pump could’ve stuck, the solenoid itself could be defective, or if someone has does some transmission work to the pump the valvetrain could be assembled incorrectly.
Matt suggestion is a good one. Unplugging the connector at the trans will tell you, if that is your issue. At least eliminate the solenoid itself, which usually is the issue. What is your base idle at? Does it stall always or when the A/C is on? There is a solenoid that increases the idle when the A/C is on and may be defective.
Being an '88 means you have the 307 4bbl with 200-4R OD transmission. I concur that it may be a stuck solenoid. If it wants to die even if you can keep it running when you come to a stop sign, it very well could be that. It's not unheard of, but it's not the only thing that can cause your problems.
They also use a vacuum operated ILC, or idle load compensator on the driver side front corner of the carb. It acts sort of like an A/C kickup electrical solenoid, which GM calls an ISS, or Idle Speed Solenoid, but those only came on the earlier VIN 9 (H/O and 442) cars. The ILC setup senses the load on the engine and adjusts idle speed based on the vacuum signal. If it's mis-adjusted, it could pose the symptoms you observe. The carburetor may also have been jacked with really screwing up your idle air/fuel mixture as well, and it could be dying when putting it into gear. There's just not enough details in your description to help zero in on what's going on.
Timing is set on these by starting the car, grounding the CCC grounding plug (green clip in front of carburetor that doesn't connect to anything) and then setting distributor timing to 20 degrees (some people use 22) at 1100 rpm in park, then ungrounding the green clip. The CCC should take it from there.
In case your emission label on the radiator shroud is unreadable or is gone, here's one specifically for your '88:
