WASHINGTON, D.C. -

Officials estimated about 730,000 units — all of which are Ford Escape and Mazda Tribute units from the 2001 through 2004 model years — are now under investigation by the National Highway Traffic Safety Administration’s Office of Defects Investigation.

ODI investigators revealed in documentation this week that they have been monitoring an issue involving the potential failure of the throttle to return to idle when the accelerator pedal has been released in these vehicles.

NHTSA’s investigative team identified 99 reports alleging incidents of throttles failing to return to idle when the accelerator pedal has been released — what officials term as “stuck throttle.”

The models in question are SUVs manufactured with 3.0-liter V6 engines.

Of this incident total, officials determined 68 reports are from owners of Ford Escapes, and 31 reports are from owners of Mazda Tributes.

“Some of the complaints, including a fatal crash incident that occurred in January, allege that the failure was caused by interference between the speed control cable and the appearance cover at the throttle body cam,” ODI said in a report available here.

“Some of the complaints also allege that the failures may have been related to repairs performed as part of safety recalls initiated in 2004,” the agency continued.

In a Dec. 6, 2004 letter, NHTSA recapped that Ford submitted a defect information report (DIR) to the agency describing an accelerator cable assembly defect that could present a stuck throttle risk in approximately 470,245 model year 2002 through 2004 Ford Escape vehicles built with 3.0L V6 engines from May 30, 2001 through Jan. 23, 2004

Furthermore, in a Dec. 9, 2004 letter, federal officials said Mazda North America Operations submitted a DIR to NHTSA concerning the same defect condition affecting approximately 121,000 model year 2002 through 2004 Mazda Tribute vehicles built with 3.0L V6 engines from May 30, 2001 through Dec. 19, 2003.

Officials went on to note that back in December 2004, Ford sent letters to franchised dealers with the repair instructions and service procedure for the Escape recall. Then in October 2005, officials indicated Ford sent dealers an updated repair procedure with updated illustrations and a warning to help prevent damage to the speed control cable while performing the accelerator cable replacement procedure.

NHTSA pointed out Mazda sent its franchised dealer letters in January 2005 but did not send an update.

“A Preliminary Evaluation has been opened to assess the scope, frequency and safety-related consequences of the alleged defect,” ODI officials explained as they sent a 14-page letter with instruction to Ford executives asking for more information about the vehicle in question.

NHTSA’s letter to Ford can be downloaded here.