Okay, so I am relatively a newbie with working on vehicles. I just purchased a 1978 power wagon and am having a problem troubleshooting this starting problem. It starts fine if I just let it sit in driveway and idle for 20 min, or even if I drive it around the block,....turn the engine off...and it will restart no problem after sitting for 20 min. But if I drive it for a couple of miles and return home and shut the engine off, if I let it sit for more than 15 min off, it will turn over slower and slower then nothing...even after sitting for an hour. I thought alternator draining battery because i disconnected the neg terminal while engine running and the engine died. Replaced the alternator, fuel filter, spark plugs. Thought the problem fixed until I drove it for a while today and same problem. After it sits for awhile after a few miles of city driving it will not turn over. This problem is driving me crazy....any advice or direction will be appreciated.