I bought this truck from my since retired boss who purchased the truck from the company. It's a 04 4.2L heritage XLT. It shifts fine from 1st to 2nd but before going to 3rd it revs up and then shifts into third and then 4th no issues. Have been trying to figure out if it's the servo in the transmission or something as small as a filter. It had 186,000 miles on it I paid $900 for it so can't complain. It's my first truck I've always had manual cars never owed an automatic. Just trying to get some info as to if anyone had this issue.

 

are there any transmission codes being thrown? some basic scan tools wont read transmission fault codes, so a professional with a proper scanner will have to scan it.
but it could be a valve body issue, shift solenoid going out or just worn out internals

 

My code reader doesn't pull anything. The only code I recently had was a camshaft sensor and I replaced it yesterday. I'll have to bring it somewhere to get the transmission codes pulled.