2005 mountaineer won't accelerate - 2005 Mercury Mountaineer

The code is for a problem with the throttle control or sensor. The computer thinks the throttle plate is stuck closed.

Are you saying it is not getting fuel pressure at the injectors ?

do you have any light to reset,check fuse.

Is the battery good in it?

Sounds like a blockage in the exhaust system. A quick fix at a local garage

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Electric Testing Techniques You Need to Know

this sounds like you rings or valve seals are leaking into the cylinder the smoking for a time is the oil burning off check your oil to see if it's getting low this will confirm if these might be the issues

when it won't crank you will need to start at the battery and work your way to the starter checking for voltage
battery - cables - ignition switch - neutral safety switch - starter

it will be more noticeable at highway speeds if you use D3 as the transmission won't use the 4th and 5th gears. This will result in higher engine revving (watch the tach) and will use more gas. The car may feel like it's accelerating faster at these speeds, but at the same time, engine braking will slow it more when you take your foot off the gas.King Scanner G3 for Toyota Tis and Honda Him

D3 exists if you are going up (or down) a mountain and want the engine to be limited to 1st, 2nd, and 3rd gear rather than "searching" for the best of 3rd, 4th, and 5th frequently (although with the grade logic Honda employs this has never annoyed me). ymmv (your mountains may vary).

D3 Doesn't hurt anything; slightly more fuel consumption as the engine will rev higher, but better to be in "D" for normal driving and let the transmission use its full range of gears

Sounds like you have a low voltage problem.Take a volt meter and battery voltage first it should be 12-12.7 volts not running and key off.Then start engine and check the voltage coming out of the alternator it should be 13-14.7 volts.If one of these are not within these specs then replace which everone that is bad.