Just want to chime in on the scan tool topic. There is a wide variety you can look at. Some that are about $25 and basic code reads. Or bluetooth readers from eBay for about $10, pair it with a smart phone and install a free app that gives you a bunch of options (sensor reads and code reader). And a ton more options, all under $100. As Bumpin said, it can help pay for itself. Food for thought.

 

I had very similar issues not too long ago. Ended up being the cam position sensor.