Possible bad ECU

[VW1300]

My bucking/stuttering problem at freeway speeds has been getting worse, and due to increasing work and family commitments, I just don't have time to keep looking for causes. I took it in to K&H ******** here in Houston, where the head mechanic has a good reputation. He's done work before for me and I've always been satisfied. He's thorough but pricey.

Anyway, after inspecting the intake flaps and EGR, and checking for vac leaks, he could not find anything amiss. He really doesn't think it's the fuel injection system since the problem is somewhat speed specific, and remarked the the injection pump is usually pretty reliable. More diagnostic work leads him to think the ECU is going bad.

The bad news is it's taking a day to get a rebuilt unit, and the cost is $1100. Now, when he puts it in - if it fixes the problem, I'm grumpy but satisfied - a bad ECU is part of roulette I decided to play buying an older digital car. if the car still runs like crap, he can return it with a restocking fee of $250. Still steep, but that's a big thing to rule out.

BUT if it doesn't fix the problem, we move on to fuel injection or weirder oddball possibilities like something going on with the SOV valve or even the injection pump itself. At what point is it appropriate to just walk away from the car? It's worth about $6000 in Houston were it running well, judging from Craigslist lately. This is my main car so I need it to run well.

Perhaps I should look at it this way - What's a '97 E300 that drives like crap worth? $2000? So spending $2000 is OK, as long as it doesn't happen often? Or approach it from the angle that's it's still cheaper than buying something fairly new and dealing with depreciation and a bigger outlay?

To complete the picture, the car is otherwise in good shape cosmetically and mechanically, I'm otherwise happy with it. I really like the OM606 motor for all the Houston freeway driving I do.

Any insight or advice from people who have been in similar situations is welcomed - how did you work out this kind of issue?

Thanks,