Transportation regulators in late 2008 decided against investigating a complaint that Toyota Tacoma trucks had "sudden and uncontrolled acceleration," according to a document released by lawmakers investigating the embattled carmaker.

The House Committee on Oversight and Government Reform is slated to hold a hearing on Wednesday about the government's oversight of Toyota, which has recently announced the recall of more than 8 million cars worldwide after numerous cases of sudden acceleration.

The document, released late on Monday, is part of a wide-ranging request of information from Toyota, the Transportation Department and the National Highway Traffic Safety Administration (NHTSA). The document is from NHTSA and is dated Aug. 27,  2008 and concerns Tacoma trucks from 2006 and 2007.

The document concludes that a review of a complaint showed that concerns were raised about the throttle control of the trucks but that in other cases a conclusion could not be drawn. "In view of the need to allocate and prioritize NHTSA's limited resources to best accomplish the agency's safety mission, the petition is denied," the document said.

Rep. Darrell Issa (R-Calif.) said that the nascent investigation into Toyota has so far raised "significant questions" about the actions of federal transportation regulators. "At the heart of the matter is determining whether Toyota acted as quickly as possible to notify regulators there was a problem and whether or not government acted as quickly and diligently as possible to investigate and act," Issa said in a statement.

The House Energy & Commerce Committee has scheduled a hearing into Toyota on Feb. 25 and the Senate Commerce Committee will announce a hearing on the carmaker in the coming days.