Why does it increase speed going down the road when I am not touching the gas?

Time for a tune up..New air filter, spark plugs,wires, pvc valve...It makes a diffrents ...Also change gas stations.. Some gas is a lot better for you car..These are the ones I would start with..If you car is running good...Try replacing the pcv valve and air filter first.... Hope this helps

sounds like either ur iac /or ur tps more then likly ur tps, throtle positioning sensor it controls ur feul intake more feul harder the engine runns, but iac idle air control it tells car more air higher idle less air tells tps less gas lower idle there all linked together have it put on a scanner that will narrow ur possiblities right down to the problem

Could be TPS sensor.

You may have a bad TPS or throttle position switch. You might be able to borrow a fuel pressure gauge and check the pressure at idle. You can disconnect the TPS leads and put the Ohmmeter leads into the TPS(Not the truck harness}. The Ohms should change smoothly as the TPS is opened.

The Crankshaft position sensor is suppose to change the voltage to the fuel pump to increase pressure for the higher RPM. If the fuel pressure does not increase the engine will lean out and die.

While a bad cylinder can stall an engine at idle, most can run at higher RPM a cylinder short.

Scanners- You need a "check light" for the cheaper scanners to work. But a good scanner bypasses the onboard computer and allows the Technician to directly question the same sensors through the cars' wiring. Such that the outside scanner can do much more than the onboard computer.

Please rate my info.

idle speed control or a vaccum leak

COULD HAVE FAULTY TPS SENSOR CLOGGED FUEL FILTER,WEAK FUEL PUMP.

if car is just idleing and the rpms are going up and down on their own then the tps is bad and need replaced. tps is located on the throtle body and held on with two screws

You are probably having an issue with your IACV idle air control valve located on your throttle body. When the IACV goes out you lose control of your idle. The car may not idle at all or you could find yourself driving down the road at 50 MPH without touching the gas pedal.

Clutch seems to be slipping, replace.

Have you changed the tps? The tps is like a dimmer switch with the idle being the lowest setting and everything above that being progressively stronger. If the switch is bad it will not advance spark or gas flow.