There is NO crankshaft position sensor on an 88.

FI ground points include the bolts on the intake manifold with several black or brown wires going to each, and one or more near the ECU, behind the passenger side kick panel. There may be others I'm not aware of. Also make sure the braided ground straps from the two rear cam cover bolts to the firewall are in place and their connections are clean.

Check the wires to the Hall effect sensor in the distributor. It's what your car has instead of a crankshaft position sensor. There is a plastic connector block on the bottom of the distributor that often deteriorates from exposure to heat and oil.

Also check the Radio Interference Suppression Relay. Despite its name, it provides power to the injectors. Open the relay and closely examine the solder joints. They are often weak, and prone to deterioration with age. This is often the cause of intermittent running problems. If bad, the connections can be resoldered. There is also a possibility that the terminals in the connector block for this relay can be pushed out of position and fail make proper contact with the pins on the relay.