1990 Ford Aerostar

Vehicle has always run well until recently. Now after a short period of driving, the motor seems to choke/gagging during acceleration such as when driving on the freeway at speeds of 55mph or more. And then will recover and resume normal operation. This has become more frequent. The fuel filter/pump have not been replaced and the last tune up was about 40,000 miles ago. This vehicle sits idle most of the time and is driven once every two weeks or so for 150 miles or less.