Really need everyones help

[RandomFact314]

I have been looking all over the internet for a long time now, tanking my car to multiple shops and have them waist my time (and gas) for no results...

I need someone to tell me what is wrong with my car...

If you don't know... (here are the facts of this problem)
-My car jerks/surges between 50-70
-Could be over 70 but I don't go that fast very often
-Seems to do it MOST at around 62 MPH
-Seems to do it at a certain throttle position more often
-Never have a problem driving city, only have problems on highway
-When I say "Jerk/Surges" I mean it goes down the road and seems to go down to passing gear and back up a gear over and over quickly (stays in each gear like 1 second)
-Yes it does do it when the engine is hot/warm also...
-Cruise control does not want to stay on, I don't know if it is related but the cruise control turns off randomly all the time now and seems to do it when it tries to push the gas a little harder at all (the SET goes off, like it does when the brake it touched)
-I thought it was a vacuum leak but I had that checked out and they said they could not find one with one of those fog machines but idk
-Trans shop hooked a computer that makes a "movie" and they said they could not get anything from it
-I have seen other people online with problems that seem very similar problems with no good answers or conclusions
-Stops jerking if I step on the throttle harder, making it accelerate more and more
-Stops jerking if I touching the petal super lightly, to where it is decelerating

PLZ PLZ PLZ help! I am very tired of this problem especially since I try to use the highway as much as I can.

I think I may bump this post a few times if I have too just because I want this resolved really really bad, I'm sure you guys understand... There are a ton of very smart people here when it comes to cars, I need help pretty bad.

[RandomFact314]

I have a program called "Auto Tech" that I put the problem in and it told me it was a possible vacuum leak... Like I said, the shop said it was no on that?

[RandomFact314]

The "Auto Tech" program says that if it did not start out small and gets gradually worse then its a bad throttle position indicator, I also mentioned that to the mechanic, they told me when they scanned it with the computer it would have showed up..

[pgfpro]

Didn't you just have the head gasket replaced?

Did it just start doing this after the head gasket or was it doing it before?

I would check the lines to the map sensor and make sure there isn't any tears in them causing a improper map reading.

Also this sounds crazy but make sure that all the engine grounds are hook back up.

[RandomFact314]

This started happening before the head gaskets...

I do not know what a map sensor is or where that is located, I will go check my grounds as much as I can

Should I hook my old crappy spark plug wire up and take it for a run to see if it was the new spark plug wires that did it? would the old ones mess up the new plugs at all?

[jamesqf]

Did the problem start suddenly, or did it gradually develop over time?

I know nothing about your particular engine, but I had similar symptoms, gradually developing, caused by a dirty EGR valve.

[SVOboy]

I would try running a DMM off the TPS and seeing if the signal is alternating oddly during your surging to see if that is indeed the case.

[Christ]

Adjust the brake pedal switch, and see if the CC stops disengaging. You're going from locked to unlocked randomly, which can be achieved manually by touching the brake pedal with your left foot, while maintaining the accelerator with your right foot. This would also tell cruise to disengage.

If that's not the problem, the TPS is the next likely culprit.

[moorecomp]

From the EBSCO manual for your car:

"Throttle Position Sensor
Operation
The Throttle Position Sensor (TPS) is the only sensor in the Engine Management System (EMS) that the vehicle operator has direct control over. The sensor is a potentiometer providing an analog signal to the computer. This signal represents how far the throttle plates have opened.

The Engine Management System calculates how much air should have entered the engine and compares this value with the Manifold Absolute Pressure (MAP) sensor or Mass Air Flow (MAF) sensor value. The EMS uses this information to calculate fuel delivery and ignition timing requirements.

The EMS on vehicles equipped with an electronic transmission utilize TPS sensor in combination with MAP and MAF sensor values to determine shift schedules and torque converter clutch application.

Some vehicles will also incorporate a throttle switch. The throttle switch is used to notify the EMS when the throttle is either at wide open or at idle.

A faulty throttle position sensor or switch due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit can cause the following symptoms.

Related Symptoms
Bucking
Hesitation
Stumble
Chuggle
Stalling on Acceleration"

I would pull the TPS and test it with an analog ohm meter. It is easier to see needle swings rather than numbers on a digital one. It should be smooth changes in resistance as you move the input to the TPS.