What the h*ll is that!?

Yesterday when my car came out of the shop after replacing 3 mounts, the idle became very rough. Especially when starting, as I turn the key to ignition, the tachometer has to jump up and down several times until it settles down a little. It even hesitate sometimes while driving today.

My max never did that before. I repalced distributor cap and rotor last week, and also checked plug wires resistance: 7K,8.5K, 10K, 13k,13K,13K, pretty normal.

Then I try to recall what happened in between.The only thing I remember that I did to my car is that: I drove it with low fuel yesterday. Could that do any harm?

Please help me pinpoint a little.Thanks.
I'm driven madmad:

 

I had rough idle too. It comes and goes but it comes more than it goes. So what i did was that I replaced the plug wires because the resistence on one of them was too high. I decided to replace all of them because it was only $60 bucks for a set of 6 bosch wires. I also cleaned the butterflies in the throttle body with TB cleaner. Boy, did it help. It took away the vibrations at idle and the acceleration became smoother. Hope this helps.

 

Thanks, Maxmoney, where can I find the step-by step instruction on cleaning that butterfly? Which brand of TB cleaner did you use?

 

When you drive low on fuel, you are sucking off the bottom of the gas tank. You have a much higher chance of clogging a filter somewhere along the line. I would replace the fuel filter and see if that helps. Just an idea. I have also had sucess with cleaning the throttle body to improve idle.

 

Its real easy to clean and detoxify the throttle body.

Just remove the three bolts, I think they are 12mm or 14mm, then flush away the carbon buildup with the spray, make sure to move the TB back and forth to get at every nook and cranny, and then use a non lint paper towel to fully clean it, and then just mount the three bolts back up and u are done.

I would recommend installing a new gasket.

 

Yesterday I got fuel filter changed and TB cleaned with paper towel.

My idle becomes a little bit smoother, but still no as good as it was. Anything I can do further?

Also, I notice the rough idle comes sporadically. Even in one mile, it changes several times. At one stop light, it idles rough, but at the next stop light, maybe it becomes smooth.

Why is that?
Did I do the cleaning right?

 

I wouldnt be suprised if your injector contacts are corroded and one or more are just barely losing contact every now and then. With your engine on, press down and wiggle your injector harnesses. If you notice any change in your motor's smoothness then you know the contacts need to be cleaned. Check all your other electric connections as well... like the throttle switch.

You might want to check your spark plugs as well.