Toyota Repair: 1996 Previa Idle problem, engine misfire, distributor cap

Question
Hello, I recently pruchased a 96 Previa with 89,000 miles. I love the van and I just had a full tune up done to it.

My question is when I have the A/C or the defrost on when the compressor kicks on it idles really rough until the compressor kicks off. The idle is bad enough to wear it makes my exauhst pipe rattle. Even with the compressor off the engine doesn't idle quite as smooth as I though it would after a tuneup. Is this normal for these vans? My 98 4Runner does not have this problem at all.

Please help with any suggestions. Thank you very much.

Dev

Answer
No it's not normal, there seems to be an engine misfire which is even more aggravated with the load of the a/c compressor, I advise you to have the engine compression tested to see if all cylinders are at about 160-180 PSI,if this checks out good there may be another problem, possibly spark plug wires or a cracked distributor cap.