help with 2.3 missing and tach reading half rpm

[ksranger93]

I have a problem with my 1993 2.3 two wheel drive five speed. Sometimes while driving the engine will act as if its running on only two cylinders and my tach only shows about half rpm. Sometimes the check engine light will come on and sometimes it will not. This problem doesn't always happen. It may run just fine or only act up for a few miles. Is one of my coils going bad or do I have something else wrong? What should I start checking?

Thanks