When I crank up the first time of the day it idles to about 3000 RPMs and then eventually goes down. Then when I put it in Drive and press the gas to go. It seems to work fine but doesn't want to shift out of 1st gear easily. It shifts after it hits 4000 RPMs... Only does it with the first gear first time cranking up for the day. Changed the Transmission filter and fluid. Fluid and filter was black and has medal shavings. Car is over 230,000 miles. I get great gas mileage. What could this be? I really need to know if I need to replace something. I'm in college and need a dependable car.. Thank you!