I have a 1994 s-10 4x4 with the 4.3L (w) that when started cold (outside temp. below 45 deg F.) will surge until it some what warms up. If I tap the accelerator a little it will idle normal for about 10-20 seconds then start to surge agin. When it warms up to normal operating temp. it runs like a champ, even when re-starting.
I replaced the fuel filter about 10k ago, fuel pump and spyder about 6 years ago. Did a tune up (plugs, wires, cap, rotor) about 4 months ago.
Any help would be great.

 

you may want to check vac lines ,cam position sensor,crank position sensor

 

Did you ever find the problem? I have the same one...

 

I didn't, did you? Summer came and the problem went away now its winter and the problem is back.

 

Same problem here too. No one seems to know. Only thing I noticed was that the timing bounces around a little. When it's warm outside, it runs fine and the timing does not bounce. I have replaced everything in my ignition system, thermostat, coolant temp sender, and cpi unit. Nothing has fixed it so I just live with it.

 

I have a 94 blazer with a 350 that is doing the same thing. I have replaced almost everything and still can not find the problem. It only surges when cold and runs great once it warms up. Would love to find the problem. If you figure it out, please let me know. Thanks

 

I had surges as well when it was cold. When i contacted a garage he took a look at it and saw some coolant leaking from the upper radiator tube where it connected to the engine itself. He said that it would run a lot smoother and surges less if he tightened that so it wouldnt leak.
After he tightened it some more the leaking stopped as well as the surges.

 

Still no fix and it pretty much surges at start up and idle and will idle high when it warms up. Had the fuel pump replaced about 2 months ago and pulled the throttle position switch which was really gummed up and cleaned it. That seemed to help at first then it all started again. Is there a way to test that switch?

 

Have you cleaned the throttle body & IAC (idle air control) valve? Is the throttle shaft smooth if you disconnect all of the cables & move it by hand?

 

Is that a 'switch' .. or a sensor? If it's a sensor, which most TPS are, it's like having an old fashioned volume control under your hood.
You really cant 'clean it' and have the effect last long.

And it will cause that sort of problems; among others, depending on what positions are flaky. You can test it... best way is with old fashioned needle type ohmmeter, digital meters do not react quickly enough.