So I recently started having problems with my transmission on my 2006 hummer H3 it has 143,000 miles on it. So the issues I am having is it shifts to all gears but it has delayed shifting and also if I have it at wide open throttle to take off it will rev rpms but will not go I have to ease into the gas to get it to go. I recently took it to a transmission shop and ran diagnostics but there was no codes and guy test drove it and hes telling me it's the transmission shaft loosing pressure and telling me it aint goin be long before I get stuck on side the road. But I'm here to see if anyone has had similar issues to verify this is the problem before I spend this kind of money and it doesn't solve my issue.

 

Look up what happens when an automatic transmission dies..... you basically described it. If you put it in gear and it slips, that is a problem.

Check the fluid level? Is the fluid red and clear, or brown/black and smells burnt. When was the last time your transmission fluid and filter were changed?