Tommy Morrison Death Certificate -- No Mention of AIDS

Boxing champ Tommy Morrison -- who starred in "Rocky 5" -- died from a blood infection ... so says his death certificate which contains no mentions of either HIV or AIDS, TMZ has learned.

According to his death certificate, filed in Nebraska, the 44-year-old died from cardiac arrest ... stemming from a blood infection known as Pseudomonas Aeruginosa Septicemia.

FYI -- back in 1996, Morrison announced he had contracted the HIV virus ... but later recanted and questioned if the disease even existed in the first place.