Car starts but it does not accelerate

Hello and welcome to 2CarPros. You say it goes bad when you touch the wires to the ECU? Which end, if it's the end on the throttle body it sounds like you have either a broken wire or loose connection in the connector. If it's on the ECU end then it can be a bad connector or the pins on the ECU board have broken free and are intermittent.
The lightning bolt is telling you the engine is in reduced power mode because the ECM isn't able to communicate with the throttle body. Unfortunately poor connections seem to be rather common on Chrysler products lately.
There should be more than just grounds though. You should have 5 volts on the pink with yellow wire, then the brown with orange and brown with dark green wires should vary from around.5 to 5 volts as a response to the throttle position, they are opposite biased (one will go up in voltage while the other goes down) when measured with a meter using the brown with dark blue wire used as the ground pin. The dark blue wires are the throttle motor feed and ground.
However, if touching the harness causes issues it is much more likely a bad connection or broken wire right where movement causes a problem.

With it disconnected there will be nothing to measure as the 5 volt bias voltage will be missing. The way it operates is by using the voltage as a reference. The 5 volts goes into the two TPS sensors on the throttle body. As the throttle moves the voltage travels through the potentiometers and sends back a different voltage from each one. One goes from 5 volts down to about.5 volts, the other does the opposite. The ECM then looks at those voltages and sends a pulsed voltage out to the motor that actually moves the throttle itself.
With the connector unplugged there will only be the 5 volt reference in the plug. The other wires are referenced to ground. The throttle motor drivers will drop to ground as well because they are not receiving any signal, they drop to ground to stop the motor from moving.
However that doesn't help much for testing. For that you will want to start it up, then gently move each wire around until you find the one(s) that cause the problem.