my 97 sport has been shaking at an idle. i just replaced the distributer cap and rotor witch i swore was the probolem ,checked the motor mounts , i also replaced plugs and gapped accordingly andreplaced wires, cleaned the carb,and my fuel system ? it has no hesitation it runs real good no codes in my computer .....what could be the probolem ? has any one had this happen to them? or have any idea more of what it could be ?[&o]

 

Did your plugs smell like gas when you pulled them? Mines got a bad FP regulator and acts the same as yours. Did all the tune-up stuff already & ran good for a couple hundred miles but then started running rough again. My FP is at 49 psi, spec is 35-45 psi. I suspect mine is dumping too much gas & 1 of my injectors flows really well #4 cyl is gas fouled & the rest smell like gas... too much.

 

how do you check the fuel pressure?

 

There should be a schrader valve (similar to a valve stem on your tires) on the fuel rail I think on the drivers side of the engine. You unscrew the cap from it, and attach a fuel pressure gauge to the valve. Have a rag handy, or better yet, wrapped around the valve area when you attach the gauge. Some fuel will probably come out. Then you can start youur engine, and see where the fuel pressure is at idle, and at various RPM's. Fuel pressure should be between 35-45psi.

My truck has that same type of rough idle, this is on my list of things to do...

 

When you cleaned your Throtle Body did you clean the AIT motor? Its the sensor of the back of the Throtle body.

What it does is regulats your idle while under preassuer.

There is an electrical connection to the sensor, unplug it.
Two tourqe screws hold the sensor in.
Once the screws are out pull the sensor streight out.
Spray it with carb cleaner ans jently wipe it off
do not move the plunger yourself, it could mess up the spring.

replace and start the truck!!

 

well i checked both and they were both fine truck still shakes and has now started to run sluggish but onley after it has warmed up but still shakes at idle

 

have you checked your compression??

 

not yet i have taken it to the shop to have them test it for me

 

you may want to have the shop check the adjustment on your distributor (closest thing to adjusting the timing you can do), my truck has similar problems and i think that's the fix

 

What about your air filter ... make sure it's clean. Also how old is your cat? A plugged cat can cause the motor to work harder & loose power.