Voltage Spike, cam position sensor, and crankshaft position sensor

I have been having an ongoing problem with my 1999 jeep Cherokee. First signs of trouble. I was driving up a hill one day nothing to bad I was in 4 wheel drive going slow. All of a sudden light start flickering and overdrive goes out, first gear is the only thing the transmission wouldn't stall out in, I look at my voltage gauge and its going above 14 fluttering from 17 to 19 volts (engine is running fine). I slow down put it in park and shut it off. Start it up nothings unusual no codes drive home. Over the next few weeks I continue to see this problem, only I start seeing this code pop up (Input Turbine Speed Sensor Circuit A Malfunction), knowing that jeeps are known to have problems with continuity (if ECM thinks voltage is low because of bad ground it can go crazy) so I took every ground off cleaning it and its connecting sure until they were shiny I then put electrical grease on them. Also I took the start apart and cleaned it up and made sure it was grounded and everything (I have heard that a bad ground in the start can cause these type of problems on jeeps depending on the year). After that the code disappeared and I haven’t seen the code sense, also stopped losing overdrive. Unfortunately it didn't stop the voltage spikes, they did however stop being as bad, it’ll only go up to about 15, 16 volts now when going up a steep hill or requiring it to work hard. So I stopped being concerned about it for a little while because I wasn't losing overdrive every time I would climb an incline on my way to work and the voltage wasn't spiking on moderate inclines. A few days later driving to work driving on a flat surface going 55 mph hit a bump (your everyday bump) service engine soon light goes on. Thought it was previous code, but it was the crankshaft positions sensor code. Jeep does seem to lack power, but still starts right up, doesn't die and the voltage doesn't spike until big hills. Replaced the sensor, in the next couple days I get two codes (crank position sensor and cam position sensor). They disappear and come back randomly jeep seems to lack power and bad gas mileage. I don’t understand what is happening.
New Parts: spark plugs, spark plug wires, coil, cap rotor, crank position sensor, all within last couple months.