95 Lesabre misfire while at idle, and overdrive shudder

My 95 lesabre is running very poorly. i replaced all 3 coil packs, new plug wires, and ac delco plugs. when it is idling, it very rough and at the muffler there is a put-put.
when accelerating it seems to be smooth until you get to 45-54mph the torque converter locks and the car shudders. my guess is i am feeling the engine miss more powerfully when the converter engages?.
i am getting very poor gas mileage.
the coolant level has not had any change it stays in the normal levels on the reservoir.
what should the resistance in ohms be on the fuel injectors?
what sensors and valves can i check. at autozone an employee told me to unplug the coolant temp sensor wire and see how it runs, then plug it back in to see what changes if any. i cannot get to that particular sensor, whats the easiest way to get to it (if i need to check that, up to you)?
on the issue of gas mileage i checked the pcv valve and made sure it still rattles, it does, but should i replace it anyways? (138k miles)
it is very frustrating dealing with this car, i have put more money into fixing it than i have paid on it, and i am basically stuck with it, i do love the buicks though and since i have put money into it why not keep it... When i am coming to a stop, the headlights dim, and when i accelerate out of stop they brighten.... a power issue???
i would really appreciate some know-how..

also i have had bad smelling heat in the car lately

thanks,
casey

Take a look at my problem, which sounds very similar to yours.
http://www.automotiveforums.com/vbulletin/showthread.php?t=452655
I didn't seem to have any change in fuel economy, but I imagine it's possible. As for your dimming headlights, if the engine is misfiring it will be turning over slower than usual at idle. If the engine turns too slow then the alternator's power output will begin a sag and can cause your headlights to dim. So I wouldn't worry about the charging system. Just keep an eye on your battery's charge until you get the problem fixed, at reduced idle speed your alternator may not be charging the battery and it will eventually run down and die on you. And this usually happens at the worst time. You might have to put it on a trickle charger once in a while to make sure it stays charged. Mosty importantly , read my thread and get that car fixed!:frown:

one thing i did was unplug the egr valve and i took it for a spin, the high speed shudder was not as bad but still evident. could the egr valve be compound with something else to make the problem? also i have a question about a vacuum line thats right on top of the engine driver side towards the middle. it goes to the driver side front of the engine and on the front it has 2 more little lines and a big line. when i squeezed the small line in the back the engine bogged down, but when i put it back on the small round orifice that it was connected to, it also bogged down, when i had it off, the engine sounded better than the first two situations. :shakehead


what other things can i check...

By what your saying it sounds like a vacuum leak,check all vacuum hoses and connections including you vacuum modulator at the transmission,good luck

A stuck EGR valve can cause driveability problems, but obviously it is not the only cause of your problems since they persist when the valve is out. I would try cleaning up the valve a bit, since you have it out anyway, to see if you can unstick it then proceed from there to try to track down the remainder of the problem. If you undertake to clean your EGR with some sort of chemical, don't expose any electrical bits which may be attached to the chemical that you use. Carburetor or parts cleaner is usually good for getting all the sticky, gummy, varnish out. I wouldn't use something like Foamy Engine Brite for that, though, since it may expand into an area where you can't flush it back out easily when you are finished.

If you have 138K on the car with the original timing set, you may want to consider replacing the chain and gears. Have you checked, or replaced the 02 sensor? The timing set or 02 sensors could contribute to poor gas mileage. Bad smelling heat could be an early warning of a heater core leak or a plugged drain in the evaporator box. Do you have wet carpet in the front passenger side?

Here is the procedure I used.

Start the car up and pop the hood. Take note of how rough the engine is running.
One at a time, unplug a fuel injector connector from one injector and then reconnect it. If the engine ran worse with the connector disconnected than with it connected, then that cyclinder is working properly. If you notice no change in the engine roughness when you disconnect the injector connector, then something in that cyclinder is not functioning properly and causing a misfire.

Do this for all six cyclinders and write down any suspected bad ones.

If you have any bad cyclinders, you will need to purchase a spark tester and a NOID light. I bought them off of ebay for about $30 total. The spark tester I purchased was an inline type like this one:
http://cgi.ebay.com/In-Line-SPARK-PLUG-TESTER-tool-Test-Ignition-System_W0QQitemZ7594299192QQcategoryZ31483QQrdZ1QQ cmdZViewItem#ebayphotohosting
please take note that I linked to that auction strictly as an example and I do not endorse that seller in any way.
I chose this type of spark tester due to the way each coil fires through two sparks plugs, and I didn't want to potentially interupt the circuit and produce a false bad reading.

You can also get the NOID light off of ebay, or an autoparts store. Make sure it is for GM cars, as they differ for different makes and years.

Once you have those two tools:

First, you'll need to pull the fuse for the fuel pump. It is (stupidly) located under the dash on the passenger side along the door frame. You can get to it the same way you get to the computer as I described in my PM. You will probably have to lay on the floor and look up to see it. It is located in a little cluster of fuses and relays, and there should be a diagram somewhere under there to tell you which one to pull. If not let me know and I'll find out for you.

With the engine off, connect the inline spark tester between the spark plug of the suspected bad cyclinder and it's spark plug wire. Have a helper crank the engine and you should see the bulb in the spark tester flash, which indicates that the spark plug circuitry is working for that plug. If you don't get a flash, then something is wrong with the wires, the coil, or even the module underneath the coils.

Next, one at a time, disconnect a fuel injector connector and plug the NOID light into the connector harness. Once again have a helper crank engine and you should see the NOID light flash. Flashing indicates that the circuitry for that injector is working properly. Even if you do get a flash, it is still possible for the injector to be clogged with dirt or the coil of wire inside the injector to be defective in some way.
If you don't get a flash, then there is a problem with either: 1. the wiring between the computer and the injector connector, or the injector connector and ground has been damaged so as the electrical signal sent by the computer to fire the injector can not reach it. 2. Something in the computer has gone bad and you will need to replace the computer.

If you reach the point of needing to test the wiring, let me know and I'll go into further detail, this post is already long enough as it is.:rofl:

i have made a new thread for my compression test results. need internal engine work all sensors and everything else was fine