what would cause trans to shift down hard when given gas and RPM goes to 3000? on 2000 Kia Sportage

When driving if you barely give it gas seems to shift fine and runs good up 40 MPH.But when you give gas to go faster or to pick up speed up a hill it sounds like your whinning out and feels like your in 1st gear, if you let off starts shifting fine. What could this be?? The trans seems fine and trans fluid looks good and no burnt smell. also it has sit for clse to 6months and before it was parked didn;t have the issue.

by in West Liberty, KY on February 08, 2013
1 answer 3 comments
ANSWER by on February 08, 2013
SCAN FOR TRANS CODES AND POST SO WE CAN ADV. OR GET A FREE DIAG AND EST FROM AAMCO THEN SHOP PRICES
COMMENT by on February 08, 2013
Spoke to someone about doing that they asked me if the check engine light was on, Way I took them that it would show no issues, will I have to take it to a dealer or mechanic to scan for codes?
COMMENT by on February 08, 2013
mech to scan codes and look at live data to get issue resolved then post findings
COMMENT by on February 11, 2013
done the scan and came up with the codes P1115, P1624, and P0302. None that points to the trans. Going to change the filter and go from there to see what happen, where it has been sitting for over 6 months. The P1115 code information is controlled and air metering, P1624 code is controlled computer output circuit, and the P0302 is #2 cylinder misfire. Can anyone tell me what I need to change or do to fix these then where to go on transmission if changing the filter doesnt help? Thank you Update: Heard that P1624 was the throttle position sensor, if it is bad will cause the issues I'm having with the tranmission is this true??