The TPS can affect idle. I just unplugged mine and tried it. It will make it idle erratic or up and down. Or at least it does on a cold engine. When you measued .8v was that on the computer side of the connector or the TPS side. The .8v may be too low. I think I remember seeing it should be less than 1.0v but more than .9v. That is why I said to search this forum. the .8 may be ok, I dont know as I have never changed one. But if I had a code that told me I had low current to the TPS, I would check for .8V at the computer terminal too. The current should be about 1 milliamp if the TPS is about 4000 ohms. Checking for low DC currents is a little more tricky as the meter leads need to be in series. IE cut the wire or have some sort of plug in adapter. Or you have one of them several hundred dollar DC milliamp meters you can just clamp around one wire.

 

It was from the Tps the volts comeing in read at 5v so I know it is getting power from the pcm. The truck really only does this when cold and a bit when stepping on the gas. Along with the code I think I will throw one in. I will try one from the junk yard first friends with the guy so he usually lets me try it before i pay. also the vacume lines I think should be done. So many of them it's crazy but they are the vinyl ones so they should not leak but they sound like it were they connect to the rubber guy told me at napa just to use seal all around their as the main line hardly ever leaks. still need to find out about that hissing sound driving me crazy not knowing.

 

The below was scanned from the manual for a Mercury Sable. It basically says even if you test the TPS and it checks good you still might have an intermittent problem your test didnt find. The typical digital multimeter only reads and updates the display about 2 or 3 times a second. So the slower you are moving the gas pedal the better your chance of seening a dead spot or high resistance spot. Event then its not 100% guarrantee you can "see" a dead spot to the wiper or signal wire. You need something that can catch 10 millisecond (one hundreth of a second) glitches or less. Which means you need an oscilliscope to be 100% sure.

Throttle Position Sensor (TPS) -check and replacement
General description
Refer to illustration 10.1 Note: If the following tests indicate that a sensor is good, and not the cause of a drive-ability problem or DTC, check the wiring harness and connectors between the sensor and the PCM for an open or short circuit. If no problems are found, have the vehicle checked by a dealer service department or other qualified repair shop.
1 The Throttle Position Sensor (TPS) is a variable-resistance potentiometer, mounted on the side of the throttle body and connected to the throttle shaft (see illustration). It senses throttle movement and position, then transmits a voltage signal to the PCM. This signal enables the PCM to determine when the throttle is closed, in a cruise posi¬tion, or wide open. A defective TPS can cause surging, stalling, rough idle and other driveability problems because the PCM thinks the throttle is moving when it is not. The OBD-II system can detect several differ¬ent TPS problems and set trouble codes to indicate the specific fault. If an OBD-II scan tool is not available, have the codes read by a dealer service department or other qualified repair shop.
Check
Refer to illustration 10.2
2 Do not disconnect the sensor connector from the sensor for these tests (see illustration).
3 Refer to the wiring diagrams in Chapter 12 and back probe the signal terminal of the sensor connector with the positive (+)lead of your voltmeter. Back probe the ground terminal with the meter negative (-) lead.
4 Turn the ignition On but do not start the engine. The meter should read less than 1.0volt with the throttle closed.
5 Open the throttle (or have a helper depress the accelerator) until the throttle is wide open. The voltmeter reading should increase smoothly and steadily to approxi¬mately 5.0 volts.
6 Also, check the TPS reference voltage. Insert the voltmeter positive (+) probe into the reference voltage terminal of the connector and the negative (-) probe into the ground terminal. With the ignition On but the engine not running, the meter should read 5.0 + 0.1volts. Note: If TPS-related driveability problems continue but these general tests don't indicate a TPS fault, have the sensor tested with an oscilloscope by an experienced drive-ability technician. A TPS often develops a voltage signal dropout of such short duration that it can't be seen on a voltmeter. The PCM can see such a signal fault and a driveability problem will result.
Replacement
7 The TPS is not adjustable. Unplug the electrical connector, remove the two retaining screws and remove the TPS from the throttle body.
8 8 Install the new sensor, making sure it engages the throttle shaft correctly. Reconnect the electrical connector.

 

YEah that might be what is happening That info helps out allot. hopefully I will get this sorted out and let you know going to try that seal all on vacume lines.

 

Well today I started ripping off all the vacuum lines I could find. They are those stupid plastic ones. Going to replace with rubber hoses. Took off the emission stuff to get at the lines hopefully this will make a difference some of those lines looked pretty bad. Thinking about disconnecting the EGR system.

 

Well started replacing those plastic lines with rubber hose so we will see how it goes so far so good. After that going to clean the EGR valve.