My '99 diagnostics manual says that the distributor rotor or rotor drive may be loose. Remove the distributor cap and check for side-to-side play in the rotor. Some rotational play is normal, excessive side play is unacceptable.
Check the wiring harness from the distributor, along the firewall, to the PCM. Check for it being penetrated and exposing wires.
The CPS harness enters the fuel injector wiring conduit then exits out the end where it curves up to the main harness along the firewall. Check the area of the harness where it exits the conduit and curves to the main harness. There have been cases where the harness chafes on the end of the fuel rail, and chafes on the end of the rocker cover.
P1391 will trigger when the failure counter reaches 96 for 2 consecutive trips.
If the rotor is okay and there is no harness defects, I suggest you clear the PCM adaptive memory and see if the CEL comes back.
CJ7-Tim has a process for clearing the PCM memory. See if you can find it in his previous posts, or by PMing him.
November 4th, Don't forget to take the trash out
If we have data, letís look at data. If all we have are opinions, letís go with mine.