I kinda experince a weird vibration at idle from my 5.2 it a 99 model truck... I replace the wires and cap and rotor which were toast could it be the cap and rotor again? it goes away when I rolling along it just when I seat at a light or stop sign.

You could have a bad mount.

if it was a bad mount wouldn't the motor rise when you goose the throttle?

You have to determine if it's a miss or vibration. That's what will be hard to do on this here internet. If it's a misfire, it could be anywhere from a cracked plug to a burnt valve or even more serious. If it's a vibration, it could be from a mount problem to balancing problem, exhaust pipe against frame etc.

I been think it might be a bad injector?? it not a driveline vibration that wouldn't be noticeable sitting with truck idling or would it??