AT THE African-American heritage parade in Harlem a couple of weeks ago, a vociferous crowd of malcontents booed black men and women in uniform cops, firefighters, correction officers, military folks accusing them of being sellouts, traitors, brainwashed fools.

That they gave no thought to the courage it takes for these men and women to do their jobs or to the battles they're still fighting against their respective bureaucracies was troubling but emblematic of a disquieting spirit aloft among black New Yorkers.

President Clinton talks about a "funk" that has enveloped much of America; years ago, President Jimmy Carter referred to a "malaise." I think what I'm sensing is an abiding distrust and cynicism that threatens to discourage black youth from being all they can be (to borrow an old Army advertising slogan). At the same time, this mood discourages many people from participating in civic life and discourages nonblacks from reaching out to us in a spirit of cooperation.

We sing of marching on " 'til victory is won" in our anthem, "Lift Ev'ry Voice and Sing," but we're so accustomed to marching that we fail to acknowledge the victories that we are winning.

For years blacks sought entry into the uniformed ranks and fought through their fraternal organizations to tear down barriers to their advancement. Blacks took pride in their achievement; theirs was one more victory won.

But that respect seems to be dwindling as we increasingly make no distinction between the few bad apples and everybody else.

The same people who booed the uniformed men and women at the Harlem parade also spoke with glee that Mayor Giuliani did not march; they talked of how they and other blacks heckled him earlier this month during the West Indian-American Day Carnival Parade in Brooklyn.

What they fail to realize is that it's one thing to disagree with him; it's another to chase him away figuratively and literally. We are a part of the city; he is mayor of all of us. When we demand a more responsive city administration and he makes an effort to reach out to us, that's a victory.

To his credit, the mayor seems to be getting it. I was impressed when he showed up at the Abyssinian Baptist Church in Harlem on Sunday to worship and to report to the people. He needs to do more of that.

He talked about the public school system and about crime and acknowledged blacks' long-standing complaints of police brutality.

"It's as much a priority for me to reduce crime," Giuliani said, "as it is to have a Police Department that is respectful of the rights of everyone."

That brought murmurs and applause, probably because it was unexpected from this mayor. More startling was his passionate plea for greater civility among the city's diverse populace. "We're all children of the same God," he declared.

Of course, the mayor didn't win over everyone. A neighbor of mine said, "I can't stand him." But making the effort is important. And, for our part, giving him a hearing is just as important.

That brings me to the Colin Powell phenomenon. That he might make a run for the presidency is not nearly as astounding as is the support he seems to have among white Southerners and Midwesterners and the distrust that engenders in blacks. Many blacks say that if whites say he's right, then he must not be. They don't see this as a victory we've sought in race relations all these years: That someone can indeed be judged by the content of his character rather than the color of his skin.

We demand that doors to hiring and promotions be opened; we stigmatize those who enter. We demand a responsive city administration; we boo the mayor and his aides. We demand access to the halls of power; we're suspicious of the man who just might have the best chance of getting there.

Something's wrong with this picture. And it'll take more than marching to address such an extreme alienation from the commonweal at a time when more of us need to be engaged as role models, as voters, as public officials.