Whining sound from under van only when i push the gas.

That is likely to be transmission issues. Check the transmission fluid and you might add some transmission improver. You can identify where the sound is coming from by using listening devices. Car Guru Scotty Kilmer did a video on this yesterday. You could also search his videos for 'whining noise'.

The video was about wheel bearings, but it shows the equipment. He also states that noise isn't always from where it seems to be.
https://youtu.be/gLHe-P27lxs

..

WHEN IS THE LAST TIME YOU CHANGED THE TRANS FILTER AND FLUID.....AUTOMATIC? START HERE!

You'll need to crawl under the van and look at the exhaust pipes before the catalytic converter. You will see it once you take a peek.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

I would be looking for fuel first a faulty fuel pump. second seeing if you have spark, bad wires or plugs or even distributor, timing could be out

You might have a shorted injector driver. Disconnect the injector harness from that cylinder and connect a noid light or a high impedance test light and start the engine. If the light stays on instead of blinking, then the injector driver in the PCM is shorted and replacement will be required.

Check bace timing and air filter element .Also ckeck fuel rail pressure

The gallop you say that is happening I assume is a cycling Normal RPM to High RPM condition. This is most commonly due to a problem in the Vacuum advance system or a loose or stretched timing belt/chain. Check the timing and see if that is fluctuating.

Tail lights and panel run on same circuit.Find place in fuse box and place a new fuse in it even if it looks good.

I thought the filter might be the issue here, on carb cars the engine tends to stall out with a plugged filter.

I have a Chevy book covering that year. Code12 is the code that flashes to let you know the ECM is working properly and there is no problem. As to the 11 code there is none in the book for that number.