1. Who pays for an engine flush? seriously all you need to do is change your oil on time. Engine flushes are counterproductive.
2. With the engine running and at the optimal temp, change your gears in the following order: P-R-P-N-P-D-P-2-P-l-P. After that with the engine stil running and the gear in park, check your fluid. If it's still too high you would need to get some fluid taken out.
3. While i wouldn;t rule out a messed up tranny, I would also look into a cylinder misfire. Check your spark plugs for the correct gap and see if any are burnt or worn out, replace if needed (when replacing spark plugs, replace all four).