Chip - Minnesota is correct in all his observations. But that is not to say you are still not making progress.
The picture of your tungsten clearly shows a fouled up tungsten! Grind it to a clean taper. It won't ball up on steel, thats an aluminum trait...
A flap disk should strip the scale off and leave you with bright shiny metal. Use the grinder at an angle to the surface, some light pressure, and push it along. Takes a few seconds, but it will come clean. I use 60 grit wheels preferably. The 80s tend to clog up with scale after too short a time.
For steel welding, you don't need to keep the rod under the gas shield. That's very true for stainless and titanium, not so for Er70-
One thing that might be happening with respect your heat, if you welded that piece at 160 amps, but still got a cold weld, you could be using too thick a filler rod. The rod added to the puddle "cools" it. So you could be using too small a cup for the lap joint (using a #5 on 1/2" plate for instance) that the HAZ is not wide enough to wet in the toes. I didn't notice the specs of the metal, cup, tungsten and rod, so this is general "speculation".
The angle at which you are holding your cup too could be contributing to hot top, cold bottom. Try to insure you're pointing the tungsten directly at the seam on a 45* angle. You might need to socialite the tip up and down a little as you go, but should be needed if the rod is the correct the diameter for the job. Lay the cup against the plate, maintain your angle, and slide along.
Don't fret, some of us mortals still produce welds like that even after years of success (of course those won't ever show up here)
Last bit of advice I might offer: If your machine has it, set the amps to a fixed number, ditch the foot pedal. Just dab and run. Focus on the mechanics of the torch/rod/weld until you get proficient. THEN introduce the pedal. This will allow you to limit your brain's activity list while learning.