95 cavalier bucking

Chevy Cavalier, 95, manual transmission, 170,000 miles.
Thought I had solved my bucking problem by changing the plugs and wires but turns out not. When I hold the needle to 40, the car will
buck/hesitate/surge. Hard to tell what's going on because it happens to fast. Also happens at other speeds as well. It isn't horrible; you just know that something isn't right.
However, when you accelerate through the gears, it's much worse and this is where you really get the bucking. As you're ramping up in second gear, the car will start bucking wildly and the only way to cure it is to shift into third. The thing is it seems to me that you're always shifting at a speed lower than normal.
Is this what a transmission problem looks like?
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No - this isn't what a manual transmission problem looks like. Good news for you, huh? This is more likely an ignition/fuel problem. You could start with a look at the TPS. Coils/coil packs would be another really good starting point - especially since this appears to be related to advancing RPM's.
What kind of maintenance has the car seen over its life? I realize you just put plugs and wires on it, but what about such things as EGR, etc.? You're certainly at a mileage point where some of these things become very real considerations.
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Yea, as a matter of fact this has been a reoccuring theme -- hestitating or bucking or surging, sometimes accompanied by stalling. Don't know if it's the same thing each time or a series of different manifestations spread out over many years.
Did change the EGR many years ago. Can't remember exactly what it was doing at the time but it did fix the problem.
Another time it was the fuel pressure regulator (which I again replaced the other day; have another Cavalier next it it and swapped it).
Fuel pump went about fifty thousand miles ago. Replaced it.
Had a problem with the crankshaft position sensor two years ago. The bucking felt similar, but it was accompanied by stalling and the check engine light would come on. The error code said crankshaft position sensor.
Then for a while I had an electrical problem. That was different though. You'd turn the key and the car would go dead. I cleaned all the ground contacts and futzed with it and it went away...or did it?
Replaced the starter years ago.
I think that's it. Thought it was a good car, but now that I line up the ailments end to end I can't really say that the only thing I did to the car was change the oil.
The TPS, huh? I'll see if I can look into that this afternoon.
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Look for a bad coil.
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Speed brakes Brian... I am remiss. I should have directed you to codes in the first place. Are you getting any codes or a CEL?
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No, this time around no check engine light, no codes.
Changed the fuel filter yesturday. Helped the performance some, but still with the bucking. Next I was going to try the ignition coil that you guys were talking about. Have a situation where I have a 96 Cavalier so usually I can try out parts for free and see if it makes a change. Usually because sometimes the parts aren't the same; for example, I know that the EGR changed from 95 to 96.
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Have you cleaned the EGR ports?. They clog with carbon and cause that type of problem.

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Yea, actually I did look inside the ports to make sure nothing was obstructing them.
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Turns out it is somehow EGR related. I plugged the vacuum going to the EGR valve with a pen and the car ran fine, albeit with an ever so slight drop in performance. So maybe I spoke out of turn when I said the ports were fine. I didn't see any clear obstruction, but they were caked with carbon. How does one go about cleaning these ports? I'm sure it's a concern having crap drop down into them.
Secondly, any tips on cleaning that egr valve? Last time all's I did was lubricate the slide with WD-40. Is there anyway to clean it out inside? Perhaps there's an obstruction in there.
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