1996 Chevy Truck cold starting

Engine Performance problem
1996 Chevy Truck 6 cyl Manual 150000 miles

My engine is very hard to start after sitting over night or for several hours. The engine turns over, but does not hit a lick. When I try a second time, it starts after several seconds. When the engine finally starts, at first it barely runs for a couple of seconds, then smoothes out to a normal idle. When running, there is good power, fuel mileage, and no miss. As time goes on, this starting problem is getting worse.
I have no idea if this an electrical or mechanical problem.
Thanks,
Buddy