Current situation..
 

Maybe somebody has seen this before..? I had the pedal in the same place the whole time.

wouldn't let me attach it.. so..

My suggestion would be to pull the cluster out and check the electrical connections since both the tack and fuel gauge needles are bouncing. Could just be a dirty ground connection....something common to these two.

Are all the other gauges okay?

I hear some funky noises in the background, is the engine running smoothly or is it erratic like the gages?

Sorry, it took so long to get back.. Yeah the other gauges are working fine.. the engine on does weird stuff when the tach gauge goes funky.

After reading what Captain wrote, I replayed video with sound up and heard the engine; this is not a loose connection in the instrument cluster!

The engine sounds like it is cutting out and then back in....thus causing the bouncing needles.

Suggest checking electrical connections to the PCM, distributor, ignition module, coil, grounds....etc. Check alternator output as well.

Good luck and let us know what you find if anything.

What LannyL81 said. Friend of mine had a very similar experience awhile back. He started in "tune-up" mode, replaced his cap, wires, plugs,etc...problem persisted and he did his coil and ignition module and problem solved. this was a 00' Blazer.
As a side note, his only did this in the rain. Dry days, ran fine.

Might want to check the fuel filter for restriction, then check fuel pressure and leakdown.

It's not the fuel filter, just recently replaced that along with the fuel pump and throttle position sensor.. for the last major problem. Now that we speak of it, it's worse on rainy days.. Think i'm going to replace those 2 when I get paid.

Ahh, a key piece to the puzzle! Secondary ignition problem. Spray a mist of water around the ignition coil while the engine is at idle. Watch for spark leakage to ground. If it leaks, replace the coil. If it doesn't leak, replace the distributor cap & rotor. Use AC Delco parts and put a dab of silicone dielectric grease on each terminal, (inside and out) of the cap. If the spark plugs and wires are original, replace them as well. AC Delco 41-993 plugs with a gap of .060"

Captain, notice you say use AC Delco original parts. I have also heard others say when replacing the fuel pump be sure to use original because others may give problems. Are these things that temperamental? Just seems like any named brand good plug would work as well. No?