The letter was released by the House Oversight Committee, which plans a Feb. 24 hearing on Toyota's safety issues.
Separately, Toyota said Friday it will recall about 8,000 model-year 2010 Tacomas in the United States due to a potential defect in front drive shafts that may result in a loss of vehicle control. The part, made by Dana Holding Corp., is also used in Ford and Nissan models, Dana spokesman Chuck Hartlage said.
Earlier Tacoma review
The automaker's earlier review of the Tacoma reported 514 complaints, legal claims and field reports about the 2004-08 Tacoma, Toyota said in an April 2008 letter to NHTSA. Among these, there were 71 accidents, 17 injuries and no deaths, the company said.
NHTSA closed its investigation of 2006-07 models by reporting in August 2008: "The information suggesting a possible defect related to motor vehicle safety is quite limited."
The 2005 and 2006 Tacomas had more unintended acceleration incidents reported than any other Toyota vehicle in any year since 1999, according to a Safety Research & Strategies consulting study earlier this month.
The 2005-10 Tacoma was included in Toyota's fall recall of 4.3 million vehicles for potential floor mat entrapment of the gas pedal.
But the House committee noted in its Feb. 3 letter to the automaker that some Tacoma drivers have reported acceleration problems even when there were no floor mats in the vehicle.
"The truck was accelerating and I was literally standing on the brake and the engine was racing and would not stop," a 2005 Tacoma owner wrote to NHTSA last March, according to the committee. "I through (sic) it into neutral and it sounded like it was going to explode!"
The complainant, who used to race cars, said he did not have any all-weather mats in the truck.
The Tacoma wasn't included in Toyota's January recall of 2.3 million vehicles for sticky gas pedals made by CTS Corp. The Tacoma's pedals weren't provided by the Indiana supplier.
Toyota also said in the letter that it does not believe there are any problems with electronic throttle control systems in Toyota and Lexus models.
The responses were to questions from the Oversight panel's chairman, Edophus Towns, who sought clarification on the technology.
"Toyota's design process is exhaustive and robust. Toyota does not believe there are any problems with the electronics of its vehicles," the company said.
"Toyota has built-in redundancies to the system and fail safe modes that allow Toyota to say with confidence that the (electronic throttle system) is not the cause of unintended or unwanted acceleration."
The manufacturer also said it recently commissioned an independent engineering study that found its electronic throttle systems performing as designed with no problems flagged.
Toyota also said in response to Towns' that it would consider expanding brake override software technology in additional models.
Brake override will be standard equipment starting with the 2010 production of Lexus ES 350s and Camrys. It is scheduled to be incorporated into most new vehicles by the end of the year.
Toyota will report back to the committee after evaluating the question of an override expansion for other vehicles, the letter said.
Robert Sherefkin and Reuters contributed to this report.