Working on a 1999 ford powerstroke it was running fine started losing power and seems to have lost power on left side of engine as it has a fuelmknock on that bank checked gasket and wiring harness it does not have a check eng. Lite lit was wondering about computers??

Run through the suggestions offered in this basic diesel engine troubleshooting link:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281