SEQ07

My 2007 Sequoia (purchased used in 2013) started giving me problems starting about a week ago. It will start every time so far. Sometimes it hesitates and sometimes it doesn't. It sounds weak and takes 3-4 seconds to engage and fire up. Once it is running everything seems fine. Battery and alternator are good. We ruled out starter since it does start, but we are not positive it isn't the starter. Anyone here have similar issue or any input on what could be causing this?