Cam Position Sensor/CEL Nightmare
 

I have a 1998, 2WD, 2.5l (ranger). A few weeks ago it died on me, the check engine and check gauge lights came on moments before. Gauges all read normal, fluid levels all fine. I hooked it up to a OBD2 scanner and got a camshaft position sensor code. I replaced the part and it ran fine, for about 20 minutes. After 20 minutes the truck did the same thing as before, flashed CEL and check gauge and shut off. I had a mechanic friend look at it, and he couldn't see any obvious problem with electronics and the new CPS tested functional. I did replace the fuel pump and filter (as they were on they're way out). The truck continues to run for about 20 minutes then dies out (it can be started again immediately, but will only run for a few seconds before it cuts out). I'm chasing wires all over the truck, but have yet to find a problem. Only other issue (I'm not sure if it's related) is the auto transmission slams into gear sometimes when it shifts from 1st to 2nd, and 2nd to 3rd. Anybody else had problems like this? Ideas?