L5 Stinson pilot reported in flight power loss resulted in off airport landing on road. Pilot reported later to be debris in the carburetor.

Narrative

On the way home to ZZZ from ZZZ1 I experienced a loss of power in cruise flight at 2;500 ft. MSL (1;500 ft. AGL) near Malcom; IA.I immediately ran through the emergency checklist; I applied carburetor heat; changed fuel tanks and adjusted the mixture between full rich and lean settings; lastly; I tried engaging the starter twice (once on each tank) and no power was restored.I lined up on a gravel road that ran East/West (I was heading West) for landing but as I got closer; I saw trees along the North side of the road and concluded this was not the best choice; so I went to my backup plan which was a road running North/South road so I turned and landed on it (to the North).The engine was at idle power with the throttle at full power. As I pulled the throttle back the engine died. I restarted the plane and found that at full throttle I only had idle power.My passenger and I assessed the situation and found no damage to the airplane or ourselves. The road was two lanes with drop offs on both sides to there was nowhere to move the plane to get it off the road. We did see a turn off into a farm field ¼ mile behind us; we elected to leave the plane where it was and chock the wheels and go for help.My passenger and I walked to two houses; there was no one home but at the third house there was a family reunion going on; so we were able to get assistance. At XA:03pm I called [the Authorities] to come out and block the road. The owner of the property said we could park the plane on his property to get it off the road. My passenger and I looked around for a way to tow it and we found a small trailer that we could strap the tail down too for movement.Before doing this; I wanted to see if the plane would start and if I could get more power out of it so I could taxi it the ¾ mile we needed to go. I found that full rich and full throttle gave me idle power; as soon as I pulled the mixture almost to idle cut off the engine roared to life; and I had power. I throttled back and taxied the plane to the farmers property which cleared the road.I called [the Authorities] back at XA:41pm to let them know we no longer needed [them] to block the road. They asked where the plane was; and I gave them the farmers address. We never did see [the Authorities]. Our Club's Mechanic showed up and did some test runs on the engine and experienced the same behavior as I did. During the final engine run the engine just stopped; no engine controls were moved. He decided to pull the carburetor off and take it home to further look at it and discuss the behavior with Central Cylinder. Once the carburetor was off debris was found in it. The debris was a foam rubber type material that is used to create a seal between the carburetor air filter and the carburetor box. The air filter was examined; and all pieces of the debris matched up to the missing piece on the filter so we're confident all pieced of debris are accounted for.The carburetor was reinstalled; but we didn't have any safety wire or cotter pins to finish the job. That coupled with the time of day it would be getting dark by the time I would be coming home so the decision was made to leave the plane; it was tied down on the farmers property.We will retrieve it in a few days.