I am going to make some assumptions that  your 20 years of running  have not been casual but a long love affair  with the sport. You have no  doubt experienced some of the common  running injuries like shin splints,  runner's knee, ITBS,  AT, PF, etc., and are not about to give up over a  little tingling in  your feet. You've worn out scores of shoes of  different manufacture and  technology, so you would know if some recent  purchase was responsible  for the problem you have now. I'll continue to  assume you tried  different lacing methods to make sure circulation was  not being cut off  to your feet from a bad tie.

The   important information within this question is that your feet are   affected but you do not mention any other body part being affected. I   mention this because Sciatic nerve impingement in the lower Lumbar area   and occasionally Piriformis syndrome can produce this symptom, but you  are most likely to have  similar sensations throughout the leg and  buttocks as well. Restriction  to the foot is an important clue and  nerves are likely to be involved  (assuming circulation is normal as  addressed above).

I've had experiences like this  related to a neuroma, which is an enflamed encapsuled nerve between the  metatarsals. These are known to affect mature  runners because it can  take years of abuse to create them. If you have a  foot condition or shoe  that is not optimum but tolerable, a neuroma can continue to grow until  the pressure begins to cut off sensation in  areas of the foot affected  by that nerve. Usually this will be  accompanied by sharp pain between  the metatarsals so I am not  completely comfortable with this as the only  possible diagnosis.

Here  is where we need more  information about the structure of your foot  versus your shoes and  socks. I once had a situation like yours develop  during a marathon  because of my attempt to control a neuroma with taping, only to find the  circulation to the foot had been cut off  so that numbness spread from  my toes rearward, and I had to stop and  remove the taping at mile 22 to  finish the race, costing me a  qualifying time. It was worth the loss at  the time because I thought I  would lose the foot if I continued, so I  sympathize.

Often metatarsal pads are used to reduce  pressure on a neuroma,  but depending on the location of the inflamed  nerve it can make them  worse, so lets take a look at your foot structure  to determine this.  Are your arches of normal height? With your feet  placed flat on the  floor, can you slide at least the first joint of your  first two fingers  underneath the center of the arch? If not, some other  issues come into  play, including lack of tonus in the TIbialis Posterior  muscle and possible Morton's Toe (short 1st metatarsal). I  assume your  podiatrist would have informed you if either of these  scenarios were  true.

If the arch is low and it is due  to the TP muscle, you must first release this muscle so it can be  conditioned to  its normal strength. While we are doing that you can  determine if  excess pronation during running is tiring the TP muscle,  and if the cause of this excess pronation is foot structure or problems  with the hip or knee. This can be a  "chicken or egg" question because  foot structure can lead to hip  problems and vice-versa, although it is  more likely to be the other way  around. To determine foot structure as  the cause, I'll include a link with illustrations here...  http://www.triggerpointbook.com/mortons.htm

While  you  may think this would have been covered by your podiatrist, the few  who  are savvy about Morton's and how to deal with it would not be  surprised  to find the orthotic you were offered did not work. If the pad used was  under the 1st  metatarsal, there are issues with that bone, possible  spurs, and the  fatty pads underneath that can render the treatment  useless and  increase your pain. At this point I need more feedback from  you to  proceed, but we can digress for a moment to cover some issues on  the  back burner.

While  seated upright on a solid chair,  is it possible for you to cross one  knee over the other without  substantial tightness or pain deep in the  buttock? Try leaning your chin  forward to see how close it can come to  the top knee, and try this on  both sides. Excess tightness in the hip  rotators, particularly the  Piriformis muscle, would make these maneuvers difficult and/or painful,  and would  be another important clue. At his point it is important to  know that  the condition or structure of your foot can cause a problem up  in the  hip that involves the extent of foot pronation/supination during  your stride, so we'll hold back on the causatives for now until all  these clues have been established.

Looking forward to your reply...