Volkswagen Repair: 96 passat, passat vr6, timing chains

Question
I have a 96 passat VR6 170000 miles. When I am driving the engine  seems to surge.  No matter what speed i am going. also it seems that when it does that,the front end seems to shimmy.I have done a tune up,put in 94 octane. gas ,injector cleaner, nothing works.Once a week I get a check engine light but no code seems to be put on the computer.Any suggestion where to look next?

Answer
Hi Ronald;
What about your plugs and wires?  Have they been changed?  Use the factory recommended plug.  Don't try some "double platinum, double throw down" spark plug.  Just use the factory plug.  Also, when you change the plugs...worry about the crap in the hole that leads to each plug, and worry about each wire.  That VR6 is an engine code "AAA" engine, and with 170000 miles on it, it may need a new set of timing chains too.  That will cost more than 2, 1996 Passats are worth.  Sorry.
I would try the plugs first, and advertize the car for sale.