NEW YORK (AP) — Wall Street finished essentially flat, with investors still confident the Federal Reserve will lower rates next week but treading cautiously as oil prices crossed $80 a barrel for the first time and the dollar extended its decline.

Investors widely expect the central bank next Tuesday to lower the benchmark federal funds rate by a quarter percentage point. The decision has not been guaranteed, though, and furthermore, many investors worry that a quarter-point rate reduction might not be enough to address investors' worries over the ongoing housing slump and credit market tightness.

"The more urgent problem than what the price of money is, is the availability of money," said John Merrill, chief investment officer of Tanglewood Capital Management in Houston. "There's such a scramble for cash."

Meanwhile, crude oil's spike above $80 a barrel, the highest it's ever been in intraday trading, and a weakening dollar fed concerns about inflation. Accelerating inflation is not only a threat to consumer spending — a pillar of the economy that Wall Street fears is weakening — but it also gives the Fed a reason to keep rates where they are.

Crude oil settled at a record $79.91 a barrel on the New York Mercantile Exchange after the US government reported declines last week in crude and gasoline supplies.

Jack Ablin, chief investment officer at Harris Private Bank, pointed out that price surges in commodities hit Americans particularly hard because they're denominated in the dollar, which yesterday dipped to a new record low versus the euro.

"I think the Fed has to pay attention to this. They need as much elbow room as they can get to make a decision they feel is right," Ablin said.

"Should this dollar continue to fall, it has the potential to limit the Fed's ability to respond to the economy."

However, rising energy prices and a falling dollar have some advantages on Wall Street. High energy costs evince strong global demand, and boost the profits of oil and gas companies, while a weaker dollar benefits US companies that draw revenue from overseas.

The Dow Jones industrial average fell 16.74, or 0.13 percent, to 13,291.65, after weaving in and out of positive territory throughout the session. A day earlier, the blue-chip index soared 180 points.

Broader stock indexes were narrowly mixed. The Standard & Poor's 500 index rose 0.07, or less than 0.01 percent, to 1,471.56, and the Nasdaq composite index fell 5.40, or 0.21 percent, to 2,592.07.

Government bond prices slipped. The yield on the 10-year Treasury note, which moves opposite its price, rose to 4.41 percent from 4.36 percent late Tuesday.

The dollar extended its slide against the euro, hitting a new record low amid expectations of a rate cut from the Fed, which would make the US currency a less attractive investment vehicle. The 13-nation euro rose as high as $1.3914 in late European trading, surpassing its previous record of $1.3852 reached July 24.

The dollar also weakened against the yen — an important currency for the stock market because of the yen carry-trade, where people invest their yen in higher-yielding dollar assets. When the dollar falls against the yen, people tend to exit these positions.

Over the last four weeks increasing energy prices have boosted the energy sector by about seven percent. Yesterday, Exxon Mobil rose 71 cents to $87.65; Chevron rose 60 cents to $89.19; and ConocoPhillips rose $1.32 to $84.85.

Gold prices also gained. In other commodities trading, wheat rose above $9 a bushel to a fresh peak, before retreating to close at $8.605 a bushel.

As Americans deal with rising food and energy costs, the housing and credit markets appear to remain far from a rebound. Treasury Secretary Henry Paulson said that financial market turmoil will take some time to be resolved, especially in the area of subprime mortgages, which are home loans given to borrowers with spotty credit histories.

Home buying is not at a standstill, though. The Mortgage Bankers Association's weekly survey showed that as rates fell in the week ended September 7, mortgage application volume rose 5.5 percent, refinance volume jumped six percent, and the purchase index increased 5.2 percent, adjusted for the Labor Day holiday.