Eletrical
 

I have a 1998 gmc 1500 5.0 that I just bought and it needed a fuel line. So I replaced the fuel line then got it running. It ran then I shut it off.then went out the next day to try to start it and it would not run so I started looking in to the fuse box and went to pull the security fuse out and put it back in but I took out #20 fuse witch is PRNDL and the truck started but went out the next day again and the truck would not start again so I tool the #20 fuse out and left it out and the truck runs what could that be