Can you use combined synopsis/solicitation for a services IDIQ type contract?

See FAR 12.601.  You will see there that the streamlined solicitation for commercial items (sometimes called the combined solicitation/synopsis) is for procurements of commercial items.  

If your new services IDIQ type contract is for commercial items, you're okay.  Whether or not it makes sense in your case is something that I leave in your hands.

The combined synopsis/solicitation is a FAR Part 12 thing, it's mentioned in FAR 13 but it's really a FAR 12 thing, you can do a combined synopsis/solicitation no matter what the IGCE is as long as it's for commercial items, you can do a combined synopsis/solicitation even for a $100 million contract for commercial services, and an IDIQ is just a type of contract. If the contract IGCE is $100 million and commercial you would use FAR 12 in conjunction with FAR 15 (unless of course you're using GSA) and FAR 12 lets you use the combined synopsis/solicitation method.