Engine Skipping

My 2003 Galant just had the timing belt changed and for some reason, now the engine sounds louder and it skips when I am going between 70 and 75 mph. It feels a little rougher switching through the lower gears and when I am going any speed above 65 mph, it sounds like the RPMs are high but when I look at the gauge the RPMs are not higher than they would be at that speed. I do not think it has anything to do with the timing belt or it would run a lot worse. The guy that worked on my car pressure washed my engine and I am not sure if something may have got wet that wasn't supposed to. He is a certified Honda mechanic who works at the dealership and did my timing belt as a side job. He cannot figure out the problem. The check engine light is not coming on so it is not making it easy to just trouble shoot with the computer. I am seriously hoping someone may have some insight as to what could possibly be the problem?? Any insight would be greatly appreciated! Thanks :)