Changed crackshaft balancer. Since then error code for cyllinder 3&4. Changed wires and plugs but when on highway blinking engine light came back on. Any1 have clue on what to do?

 

Welcome to MF! .... need to check on the S197 V6 section!

 

try taking off the wires and making sure none of the caps are burnt. you can also check and clean the MAF, ive heard it helped a few ppl. then if that doesnt work, i would probably take it in. it sounds like spark or fuel tho

 

What's the specific DTCs (codes)?
How does it run?

 

A flashing engine light is usually the result of an engine misfire.

This happened right after replacing the crankshaft balancer? If so you have to assume it is related to that. Does the ECU get it's ignition reference signal from the balancer?

That's where I would start.

 

No. GET THE SPECIFIC CODES AGAIN. Go from there.
A 'flashing light' can mean lots of different things. These cars have a lot of built-in monitoring and diagnostics. Use it!