MY 1998 CHEVY BLAZER HAS CLICKING NOISE. IF LET OFF THE GAS IT STOPS THEN AFTER AWHILE THE NOISE GOES AWAY.

i have an 04 and it was doing the same thing i have dual climate control so the noise was the rear climate control blend door actuator.
replaced it clicking is gone.

YOU NEED A STARTER

I know this sounds really stupid but push the reset button on the tripometer on the gauge cluster I had the same problem and it took me about 2 weeks to figure it out and about1 1/2 seconds to fix I just pushed the button and the noise was gone.

does sound like lifters to me which most can be adjusted

The problem could be coming from the brake-pads or the caliper sliders. If the Stainless Steel shims are missing or worn-out then it can make a constant clicking sound that disappears when you applie the brakes. The same goes with if the Caliper Sliders are dry or loose.

There is usually a fuse, and may also be a kill switch that stops power to the fuel pump in the event of a collision.

Could try to have a friend ride with you & touch different areas of the dash while vibration appears as many items could have come loose

 It could be your brake light switch may need adjustment or it's faulty. Try driving with your cruise control on and see if it dis engages or see if your brake lights fliker as your diving which is the harder of the two. 
Good luck and hope this helps.

Check the ft diff actuater. Sounds like the ft diff isn't complelely disengaging when in 2 wheel drive. Also I'm not sure but I think that the fr driveshaft should not be turning when in 2 wd. If it is turning then you could have a problem with the transfercase.

I have a 98 blazer that makes similar sounds but it's pieces of the dust shield off the rear wheel assembly that got down inside the brake rotor. Only happens when the truck is going forward