Hard staring sometimes

The check engine light should provide clues. You could have a synchronizer making noise - it can make a squeak, chirp or tick noise. Or you could have a vacuum leak causing lean codes (P0171 P0174...)... The mechanic who checked it really should find something with your check engine light at the very least...

I had the very same problem with my 2005 and had it checked by a mechanic he could not find the problem.I was talking to a guy I work with and he told me he had worked on one before and he ended up changing the battery to solve his problem.The battery was getting weak and this model Ford does not like a weak battery .I changed my battery and no problems in 3 months.