99 bravada sputter & backfire

99 bravada with 148,000 miles on it. The guy i bought it from was a mechanic and says the motor and tranny have bout 90,000 on them. On to the problem. It has trouble starting and when it does it idles rough. When i floor it in park it hesitates sputters backfires and at times dies. It is not even driveable to move up and down the driveway. It was trowing the code for crank position sensor. I changed it. Ran good for bout 4 hours and started again. I'd take it out and wipe it off. Then it would run ok. For a little while then start again. Now i can't drive it at all. I took the sensor back and they replaced it but no help. Any ideas??:banghead:

How does the inside of the distributor cap look?
Is it still throwing the CPS code?