kyle may

I have a 98 Chevy k2500 with hesitation problems and can't figure it out it has no o2 sensors and its oil pressure goes from 40 driving to 20 at idle and I just don't have the money to fix everything I just wanna know that many cause of this problem it only has one spot to put a o2 sensor on exhaust system and I did find a plug witch wasn't connected to anything and only had a orange wire and I think there's a short somewhere causing all of this to happen


Thanks for all the information I get