Hello, I just started having this problem as of this morning. I drove to school completely fine but after class I started the truck up and it drove fine but the idle would drop down to 300-400 RPM. It was bothering me so I pulled over and tried turning the idle screw up a bit but this did not help at all. So my truck is shuddering and I'm waiting for the light to turn green, it does and I go and it has very weak power until I hit around 2000 RPM and then the truck was fine from then on. I tried driving it later in the day and it did the same thing. I don't know what would cause this. Tomorrow I plan to at least spray the throttle body down with carb cleaner. Anybody have the same problem or have any thoughts on what could cause this? I couldn't find any definite answers using search. Forgot to mention, 86 22re w/ 5 speed.

 

Try the 02 sensor, you can get it tested at most auto repair shops....Mine was doing the same thing for a while, cept mine is fuel injected. Mine was at the point where you would have to floor it to get it to go anywhere, could also be catalytic converter, or fuel injectors, fuel filter, fuel pump, vacuum leaks....but try testing 02 before anything, then cat, then do the other stuff.

 

His is fuel injected too...

it sounds like a 02 sensor could do this.. also check to make sure all your plug wires are attached and in good working order.

 

I don't know what could be wrong with your engine, but I just wanted to advise you against using carb cleaner to clean out your TB. Use some TB cleaner for fuel injected vehicles.

There is a reason for this, I read it somewhere, but I forget :/

 

ok thanks for stopping me before I did that.

 

If it suddenly dropped your idle, TB cleaner is not the first thing you should try. There is a reason it dropped suddenly. First thing I'd check for is a vacuum leak. Use an UNLIT propane torch and direct it around all vacuum hoses with the engine idling. If it idles up at any point, there is a leak there. Also take a good look at the plugs/wires for any connection problems or spark jumping (you can do this in the dark and it will be very obvious). Good luck.

 

+1.. probably vacuum.
If you don't want to use propane, or don't have it, you can use any non-volitile engine cleaner/degreaser.