That's a bummer. I think there's a couple threads about that, might be worth searching and seeing if there's some special tricks. I wish I had some advice but I've never done that before. Since you're just trying a quick ECM swap to diagnose your jerkies, I don't think it'd be worth delving into the security transponder bypass stuff. I think that entails opening up the ECM, buying a little PCB, desoldering and soldering, etc. Seems like a lot of trouble for a long-shot attempt to figure out the jerkies...Hmmm... Can't seem to get the car to recognize the donor key no matter how I position it.
Wanted to update this post. I think I spoke too soon. While cleaning the EGR plate and installing a new valve has greatly improved the problem, it isn't fully solved. Anecdotally, the herky jerky seems to get better after driving the car for about 10 minutes. Also, it seems to be worse on some days and better on others. So, I don't think my problems are fully solved. I think my next step is to clean the passage way below the EGR valve.I had previously disconnected the EGR valve and with it disconnected, the herky jerky stopped. So, last weekend we cleaned the EGR plate. It was about 75-80% clogged. But that only offered slight improvement. Then I ordered a new Wells 4F1890 EGR valve from Rockauto. It arrived on Wednesday. We installed it and took it for a drive. Unfortunately, there was no change. But then, my son noticed in the Wells EGR valve box, a piece of paper suggesting that you disconnect the 12v battery for 30 minutes so that the system will be forced to learn the new EGR valve. 30 minutes seemed stupid to me. But I did disconnect the 12v battery for about two minutes. Then I reconnected it and took it for a drive. Still had bad herky jerky, inititally, but I kept driving it and after about 7-8 minutes, it started getting better! By about the 10 minute mark the herky jerky was dependably gone. I then continued to drive it for about 1/2 hour and it has been gone since. We took it for another drive last night, and it was still gone. I don't know whether it was disconnecting the 12v battery, or just driving the car for longer than might be considered necessary, but our problem appears to now be solved.
Confirmed that the fuel pressure system is operating within the proper range of pressure. So it is something else.Even though disconnecting the EGR valve seems to stop the herky jerky, I'm becoming increasingly confident that the problem is unrelated to the EGR system. It seems like something else is interacting with the EGR system. I have a recurring P0172. So, at this point, I'm thinking that my next thing to check out is the fuel pressure and then possibly the TPS.
Just stickin my 2cts in. I find that the jerky behavior happens when the car wants to come off of lean burn. The transition should be smooth but maybe some combination of old O2 sensors or clogged cats causes the transition to be rough. I drive a piece of hwy where LB is very dependable to acquire. At almost the same physical location every time, I get the jerk. If I let it happen, in other words, keep my foot steady, the FCD will sharply drop to about 50 as the engine goes into purge. After 10-15 seconds, the jerk returns as the car makes a "forceful" return to LB, and the FCD jumps up to 80, 90 and higher. I've never really minded the jerk because it lets me know I'm either entering LB or coming off LB.Thanks for the info. My plan was to replace the secondary O2 sensor in hopes of solving my problem - based on the work that you've already done.
I had to look up what a jobber bosal was...(if I found the right part), I've called that piece a "test pipe". Interesting that w/out a CAT the problem would be cured.
I think you're correct that when the CPU is trying to keep the engine from polluting and protecting the CAT from burning up, it's constantly making adjustments - creating the herky-jerky feel.
I am not getting a code for any faulty part and I know that CAT is very expensive - I'll try and find an inexpensive secondary O2 sensor and replace it and report back.