Chevrolet Repair: Chevrolet Dealer/LeSabre, damsel in distress, vacuum leak

Question
HI!  I sure hope you can help this damsel in distress!  Yesterday, I took my 1992 LeSabre to the Chevrolet dealer for repair (I live in a small town) They said the ignition coil and ignition coil module had shorted.  I had been unable to drive uphill without downshifting.  They replaced the ignition coil and stated the module test was ok.  Now, it is worse than before -jerking, bogging down and trying to die when I put on my brakes.  Also, last fall I replaced a vacuum line when it was doing the same thing. I don't know whether to take it back or what to do now.  Could you give me some direction?  Thank you so very much for any advice!

Answer
Hello Carolanne,
I would be tempted to tell them to put the old one back on, not charging for it since it was apparently not the problem, then check the EGR valve, which may be seating on some carbon, thus creating a big vacuum leak. Then when you deplete more vacuum with the brakes,(vacuum power assist), the engine can't run on just that air.
It is also possible that the brake booster is the complete problem. To find out, you can remove the vacuum hose from it to the engine, and 1...see if the booster holds stored vacuum with the engine off, and 2...see if removing and plugging that hose makes the engine run better. Be careful during that #2 test, though, as you may have one application of power brakes with it disconnected, but will quickly fall back to non-power brakes, requiring much harder pedal pressure to stop.

A less likely problem, but one I will mention, is the possibility of a broken valve spring in the engine.
Try the vacuum stuff first.
Van