Is it misfiring or is there any suction sounds coming from the engine? Check your vacuum hoses see if ones kinked there might even be one with a hole in it. It sounds like a related issue to the other thread.
1957 Buick Special Estate Wagon
1996 Mustang GT (sold)
1997 Mustang V6 (sold)
2002 Jeep Grand Cherokee Laredo (sold)
2007 Jeep Grand Cherokee