Jerking at slow speeds

Problem is, after car warms up at slower speeds, 15-37 mph the car bumps and jerks. This is real annoying and I'm noticing that it's getting worse. Also after car warms up, if you put the car in gear the idle will drop and surge up or stall out. If if surges up it will do this about three to four times before it takes off.. This is under normal light acceleration.. No hesitation on heavy pedal. Also the jerking and bumping is at cruise only, not at accell or decelleration.

To recap. a.. Replaced Throttle Pos. Sensor b.. Replaced MAP sensor c.. Replaced O2 sensor d.. Replaced Coolant Temp sensor (Last fall) e.. Replaced Thermostat (Last fall) f.. Replaced Plug wires (Last fall) g.. Replaced Spark plugs h.. Removed and cleaned Throttle body i.. Removed and cleaned Idle Air Valve/sensor j.. Replaced all Corroded and bad looking vacuum lines k.. Vacuum leak test, No leaks. I sprayed all vacuum lines and all areas of intake to see if there was any leaks.. Nada. But I have replaced two vacuum lines under the intake leading to the Canister purge solonoid.

I'm out of Ideas.. So please lets throw some out here.

Didn't see it on your list. EGR valve? I cleaned mine, but it still jerked and hesitated at low speeds. When I finally replaced it all was well. (code 32 I think on it).

Oh, I had one of those cracked hoses under the manifold too. Thought it was the purge solenoid (code 26 on that one) but it was just a cracked vacuum hose. Mechanic says all the oil that spills over runs down the back and eventually cracks developed around there (SL2 DOHC engine).

Mack

What I did to prevent the cracking of teh hoses below the manifold was to replace the runner vacuum hose with fuel line hose.. This will hold up better..

But I'm going to try to test teh EGR,, at 70 bucks fir the valve I dotn want to spend that and not cure the problem.

Anyone know how to test the egr?

jerked and hesitated at low speeds. When I finally replaced it all was well. (code 32 I think on it).

was the purge solenoid (code 26 on that one) but it was just a cracked vacuum hose. Mechanic says all the oil that spills over runs down the back and eventually cracks developed around there (SL2 DOHC engine).

Have you taken the car to the dealer for a diagnostic or read the codes? If it saves a person from buying ONE part they don't need, it has paid for itself. And it beats guessing.

You didn't mention what year/model. If it's pre-OBD2 (91 - 95), you can read the codes yourself with a paperclip. Instructions are at

Refer to Diagnostic Trouble Code Information, and Diagnostic Trouble CodeChart for 1st Gen Saturns. Or, people posting here have said you can stopby any Auto Zone and have them read the codes for no charge. Lane [ l a n e @ p a i r . c o m ]

1991 Saturn SL2 1.9L DOHC

I fixed the codes there were present.. O2 sensor that was reading rich, and Map sensor reading voltage high or low vacuum..

so far 3 weeks and no codes.. Gas milage was increased from 10 mile per gallon to about 21 miles per gallon.. so thats ok.. The only thing I need to solve is this jerking condition..

I really dont want to spend 100 bucks on diagnotic and then the money to fix what ever is wrong.. The only things I can thing that it may be would be EGR or IAC valves..

Is there a way of testing the Idle Air control valve and the EGR valve..

here the IAC is 40 bucks and the EGR is 80 bucks.. So I want to spend as little as I need as you can see I have alredy spent enough on this car..