One reason that your truck might start to shake when the gas pedal is pressed is because the tires could need to be balanced. The problem could also be your shock absorbers, or struts.
* It has less to do with the gas pedal as it has to do with parts affected by acceleration.
With truck in neutral, and brake pedal pressed switch to 2wd it should click then go off.
Check your Caliper adjustment pins. They my be sticking.
check your clutch slave cylinder for leaks,its bolted on your transmission,about 20 bucks
Check for warped front rotors. under slight brake application it may not shake. But under hard braking such as getting off an offramp the truck will shake and the brake pedal may pulsate slightly. Chances are real good this is your problem.
sound like a bad universal joint, vibration more noticable under load?
Most probably
On a 2005 Ford Sterling truck, the brake light switch is typically located near the brake pedal assembly. It's mounted on the brake pedal bracket and is activated when the brake pedal is pressed. To access it, you may need to remove some panels or trim under the dashboard. Always consult the vehicle's service manual for specific details and diagrams for your model.
The accelerator pedal. Also known as a gas pedal.
On a 7400 International truck, the stop light switch is typically located near the brake pedal assembly. It is usually mounted on or around the brake pedal bracket, where it can be activated when the brake pedal is pressed. For precise location details, it's advisable to consult the vehicle's service manual or wiring diagram.
Could be a problem with the lockup converter (overdrive).
The truck needs a tune up.
Because you're stepping on the gas pedal.