97 Aerostar- chugging

I have a 97 Aerostar with 161K miles. Not driven hard. Regular oil changes and most everything up to maintenance levels. Van started chugging about 3 weeks ago, both in reverse and forward. Felt like it was going to stall out. Tune up done, new plugs wires (3 times now), fuel system flush, EGR valve to the tune of $1000 at Firestone. Now, after redoing the tune up, plugs and wires, van is running worse and they want to take the head off to see if its a stuck lifter. Thats only $2500- no thanks!

Problem seems to go away mostly after the engine gets up to temperature. I know it SOUNDS like a stuck lifter, but how much money do I put in this?
Firestone has reccomended "Just live with it". They also admit they have no idea what is wrong.

I am kinda between a rock and a hard place. I'd love to get a new truck/van/utility vehicle but $ are tight these days....

Any help here is greatly appreciated!

Normally you can remove a valve cover and watch you can pick out a stuck lifter quickly. Don't pay $2500.00 unless you are sure. They sell a treatment that will help out most times. Auto Zone or Advance sells it. Try this first as it is a lot cheaper. Normally a lifter will free up when the engine is at operating temperature.