I have a 1987 2.5 Automatic with 170,000 mi.
The problem is that the car will intermittently lose power while cruising. The check engine light will come on and the speedometer will fall to zero for a brief second and then pick right back up. I have recently changed the fuel filter but it had no effect.
No DTC is being stored in the computer either.
Once in a while the check engine light will pulsate at what appears to be engine speed --really weird.
Also, sometimes it will high idle for no reason as well.
Any help will be greatly appreciated.
Sounds like an intermittent electrical problem. Start with the basics, have the alt and battery tested. Check all grounds and power feeds. Might have n main PCM relay thats giving up on you. This one might require some diagnostic equipment to find. Good luck