I have a 2002 neon 5 speed and when I take my foot off the gas pedal the car jerks and surges what could cause this? It is worse at higher speeds and it causes the steering wheel to vibrate. I have replaced power steering pressure switch and power steering pump, had alignment checked, had axles checked, and tie rods and motor mounts. I have had this problem for close to a year and no one seems to know what it is please help.

Test the alternator. A bad diode within the alternator can have some crazy ripple effects on sensor signals.

I assume the car you are talking about is your 1968 Dodge Dart GTS with a 4-speed manual transmission. The engine has a special camshaft, Chrysler P/N 312044, which has a 60 degree overlap in the valve timing, since the engine is built to rev in excess of 6,000 RPM. The problem with your car is obviously a leaky accelerator pump. Why don't you get a car that (1) does not have to run on premium gas (because of its 10.5:1 compression ratio), and (2) uses fuel injectors instead of a wild 4 barrel carburetor made for 1/4 mile drag racing? I happen to know that that is the car you are referring to, because you did NOT say that it WASN'T!

Check for fuel blockage in filters could have a small screen filter on the inlet to pump pipe.

Is the car equipped with the Automatic Transmission?
If so, read on.
Otherwise skip to the end and answer some questions.

POSSIBLE SCENARIO:
I have observed a condition where my car surges slightly when the torque-converter clutch (TCC) cycles between lock and unlock when driving on an uphill grade.
First some basics and history that will explain why the TCC is used.

Engine, Torque Converter, TCC, and Transmission relationship--
The TCC allows for a solid connection between the engine and transmission which allows the input to the transmission to rotate at the same speed as the engine.
Without a TCC, there is slippage between the engine and automatic transmission. The slippage is greatest at low engine RPM. That is what allows the engine to run with the automatic transmission in gear, like when you first shift into gear or stop at a stop sign. When the throttle pedal is depressed, the engine RPM begins to increase and the torque converter begins to slip less and less the more the engine RPM increases. The car moves. But even at cruising speeds the torque converter slips slightly. Engine RPM is greater than transmission input RPM, which is realized as slight decrease in fuel efficiency.
When acceleration is complete and a constant speed is being maintained, the engine power output is reduced to the point where the TCC can engage and eliminate any slippage between the engine and transmission. If the car has a tachometer the engagement of the TCC can be verified when a slight reduction in engine RPM observed without a corresponding change in vehicle speed.
One method used to test the operation of the TCC is as follows:
Find a flat section of road where it is safe to perform the test.
Reach a steady speed and keep the gas pedal depressed with one foot. While observing the tachometer (or listening for an increase in engine RPM), with the other foot depress the brake pedal enough to activate the break light switch but not enough to engage the brakes. When the brake light switch activates, the TCC receives a signal to disengage. With the gas pedal being held steady, release the brake pedal and the engine RPM should decrease when the TCC engages.
Old cars with Automatic Transmissions did not use a TCC. I believe the TCC was put in use in an attempt to increase fuel economy.

MY EXPERIENCE WITH SIMILAR SYMPTOMS
The condition that causes that issue on my car is this:
- A slight uphill grade increases the load on the engine.
The car tends to gradually slow and it is necessary to depress the gas pedal to maintain speed.
- Depressing the throttle pedal (manually, or automatically with cruise control engaged) signals the torque converter clutch to unlock when the load increases slightly. (A more drastic load increase would signal the Transmission to downshift to a lower gear.) The corresponding increase in engine RPM and output is enough to compensate for the reduction in speed. When the vehicle speed, engine RPM, and throttle position stabilize to the point that the TCC will engage and the engine RPM will reduce in correspondence with TCC engagement. Now, if the road conditions have not changed, power output is not enough to maintain vehicle speed. With the increased load caused by full engagement between engine and transmission, and the cycle (surging) repeats itself until the road conditions change.

Does that help?
If not:

QUESTIONS
Please define the symptoms.
What are the road conditions when the surge occurs? (A slight uphill grade?)
What is the frequency of the surge?
Does the engine power output have a noticeable surge?
Is there a speed change related to the surge?
Does the tachometer move up and down with little or no change in vehicle speed?
Are all instrument indication in the normal range?
What else has changed?

Good luck!

The idle speed in your car is controlled by a computer (known as the PCM), the computer controls a valve called the Air Bypass Valve, this valve and the throttle valve get full of sludge from fuel vapors and combustion "blow back", this causes the valve to stick or move slowly, this in turn causes surging (speed goes up and down) in the idle speed of the engine, it is the most common reason for idle surge on any fuel injected gas engine up to about 2004 when car makers starting using electronic throttle control. To clean the idle speed control valve and the throttle valve do the following.
To correct this problem Buy a can of throttle valve cleaner (it is made by CRC) from the local auto parts store, NEVER USE CARB CLEANING SPRAY, IT DESTROYS THE ANTI-STICK TEFLON COATING, spray it into the air intake through the throttle body of the engine until you have used about half the can, you will need to hold the idle up while you do this, it will try to stall, after this shut the engine down and disconnect the Negative (-) battery cable for 5 minutes. The intake is now clean, if you continue to have the idle speed control problems you may need to seek the help of a professiona

If you smell the gas I would have it checked you may be dumping to much fuel into the carburetor or may have a fuel leak which can cause a fire.

sounds to me that your clutch needs to be replaced. There is no adjustment on the clutch pedal. It sounds like the fly wheel will need to be surfaced also.

after checking fluid level is correct, try this, to see if it improves...
into drive,let car accelerate without any gas(do not touch pedal)to max speed (about 30/35mph).stop,then with 1/3rd gas pedal,accelerate to max speed(do not move foot)stop,then foot hard to floor,upto about 60mph,then stop.then only using a max of 1/3rd gas pedal,drive for about 15miles.you have just reset the drivetrain computer setings....the car is fitted with a computer controlled fuzzy logic gearbox,it will try to make you drive as eco as poss,but if used harshly the gearchange can be harsh up and down.....
if driven gently 4th will engage at 43 mph,with a slight clunk.

idle air speed control valve(iac),too low idle or driveline problem like play in the drive shafts. if you put it in park and give it to say2500 rpm and let go of the throttle,does it return to 900rpm?if it dips down to 5 or 600 then to 900 the iac is bad.

Common problem with the Intrepid, i had a '99 and a '04 do this to me and it was the Transmission output shaft speed sensor both times.

eventually when the problem gets worse you will get codes for the sensor as well as codes like "2nd gear ratio incorrect". It can cause a lot of strange problems like shifting into the wrong gear. Sometimes it will also try to shift into third gear when leaving a stop sign causing it to rev high and then drop into first gear.

The dodge guys charged $90 bucks to put one in for me and i did the other myself, located on the drivers side of the transmission near where the cv axle comes out. there are two sensors there, one is Vehicle Speed and the Other is output speed. I believe they have a different number of wires so just match up your new one.