Maryland upheld a landmark ban on cheap guns, abortion foes won major victories in Michigan, Colorado and Arkansas, and a measure that could sharply cut auto insurance rates held a slim lead in California Wednesday.

In other election results, California voters overwhelmingly rejected an emotionally charged AIDS initiative that would have forced doctors to report AIDS patients in order to trace everyone they might possibly have infected. However, Californians approved a referendum allowing AIDS testing for people accused of certain crimes.Massachusetts and Nebraska residents Tuesday gave votes of confidence to nuclear power; the tax revolt suffered setbacks in Colorado and Utah. Oregonians rejected what would have been the nation's toughest anti-smoking law, while Californians approved a 25 cent increase in cigarette taxes with the proceeds used to promote health. Florida and Colorado made English their official state language. New Yorkers approved a record $3 billion borrowing to repair roads.

In all, voters in 41 states faced 238 statewide ballot questions - 29 in California alone.

In California, where auto insurers, lawyers and consumer advocates waged a record $75 million media battle over five conflicting insurance-related ballot measures, voters rejected three of those propositions and were defeating a fourth. However, late returns showed that a Ralph Nader-backed measure that would slash rates by more than 20 percent moved into the lead. With 83 percent of the precincts reporting, the proposition was backed by 50.4 percent and opposed by 49.6 percent.

The AIDS measure that would have forced California doctors to report the identities of AIDS sufferers was defeated by 64-36 percent with 40 percent of the precincts reporting. The plan was backed by tax reb-el Paul Gann, who contracted acquired immune defiency syndrome in 1982 from a blood transfusion.

The other AIDS measure, which won by 64-36 percent, is designed to help protect rape victims and law officers who fear they may have been exposed to AIDS or other communicable diseases.

In Maryland, the state's 6-month-old law that bans cheap handguns known as "Saturday night specials" won by 58-42 percent despite a more than $4 million media campaign by the National Rifle Association, which feared it will encourage gun control elsewhere.

In Michigan, voters approved a ban on state-financed abortions for poor women except to save the life of the mother. With 64 percent of the precincts reporting, the ban won by 58-42 percent.

Coloradans likewise voted against state-funded abortions, by 60-40 percent. With 95 percent of Arkansas' vote tallied, a proposed amendment that would protect life beginning at conception and forbid state-financed abortions held a 52-48 percent lead.

In Massachusetts, voters rejected an initiative that would have shut the state's two nuclear power plants. With 56 percent of the vote in, 68 percent voted against the plan that was opposed by Gov. Michael Dukakis.

Nebraskans decided against becoming the first state to withdraw from an interstate nuclear waste compact.

Among the more stringent tax-cutting measures, South Dakotans were rejecting Proposition II, which would have rolled back property taxes and limit future increases, by 63-37 percent.

Coloradans defeated a "Taxpayers Bill of Rights Amendment," which would have cut income taxes about 10 percent, limit property taxes and require voter approval on future hikes except in emergencies. The measure lost, 57 percent to 43 percent, with 20 percent of the vote tallied.

In Utah, voters overwhelmingly rejected three tax initiatives that together would have lowered state and local revenues by $329 million. (Story on A1.)

Nevadans also voted on a constitutional prohibition on income taxes.

A "Fair Tax Amendment" that would have made it easier for the Arkansas legislature to raise certain taxes failed 62-38 percent with 33 percent of the precincts reporting.

Oregon voters rejected an ordinance that would have banned smoking in most public places. With 36 percent of the ballots counted, the measure was failing by 61-39 percent.

But 58 percent of California voters were endorsing a 25-cent hike in the cigarette tax, with 14 percent of the vote counted. Proceeds of the tax would go toward promoting health.