i heard that it was probably one or more oxygen sensors . can i replace only one ?
Sure. Pick one.
Seriously, if you’ll post what the codes were and what diagnostics were done we can render much better advice.
There’s less than a hundred parts on that truck that might turn on the check engine light should they fail. If you keep throwing parts at it, you will find it eventually. Or, you could get the diagnostic code(s) and start proper troubleshooting from there. They are easy to get on your truck, all you need is a paper clip. (No code reader required.) Search this forum, the method to read the codes has been given several times.
Is the engine a 4, or 6, or V6, or V8, or V12, or what?
It’s been over 2 hours since someone posted, so, I guess you aren’t really serious in getting an answer.
94 Explored had only one engine option. The 4.0 v6 with just two O2 sensors.