An end-to-end check of wiring integrity may be useful, particularly earth points and interconnections. You’ll need to remove both front splash shields. Check the connections at each kick panel, it’s always possible something simple as a poorly seated connector is your issue.
If the engine sometimes runs flawlessly across all ranges of operation, you can fairly much rule out issues with timing gear, and valves. Oil pressure would be perhaps worth monitoring with a mechanical gauge but I doubt there’s pickup or pump issues.
I’m also assuming the
PCM hasn’t had an aftermarket tune flashed onto it.