Why is my '02 Mits Eclipse car lagging in lower gears.?

Over the past few weeks my '02 eclipse has seemed to be lagging dramatically especially in first and second gear. its a v6 manual and it has never been doing this before. when i try to accelerate from rest, it takes forever, even when i give it as much gas as possible. the higher gears seem to work as normal and after about five or ten minutes or so, the lower gears seem to begin working as normal again. it's extremely frustrating trying to start off at a red light but can barely even get going. What could be the problem????