Fenix PD36R sounds like it may fit the bill.
Unfortunately, that won't work.
The Fenix PD36R manual includes a graph showing runtime and output at all modes. The only mode it has higher than 1,000 lumens is its 1,600 lumen turbo. From the graph turbo output steeply declines to a max of 800 lumens or so by the 20 minute mark. Then it gradually declines over the next 2 hours to approximately 650 lumens. Then output rapidly declines and terminates somewhere before the 3rd hour. If you do a Google search for "Fenix PD36r Flashlight review". The third item on the list, Zeroair's review, has photos of the manual including this chart.
As other posters have mentioned, what you want simply doesn't exist right now in a compact single-cell light. There aren't any single-cell compact lights that can sustain 1,000 lumens for 3 hours. LED and battery technology is not quite there yet. If you really must have 1,000 lumens for 3 hours, you could get a multi-cell light, but these tend to be quite large and heavy. You're not going to be able to pocket-EDC a multi-cell soda-can sized light.
If you really want 3-hours of runtime at 1,000 lumens in a semi-EDC'able format your best bet is probably to get something like the
21700 Zebralight PLUS a spare battery.
Zebralights are known for being extremely efficient with top-notch heatsinking. You're probably not going to find a more efficient compact single-cell light that is able to sustain 1,000 lumens without overheating. Carry that around with a spare battery in a pocket battery carrier. When the cell in the light runs low, pull out your carrier and swap batteries. With a spare battery you should have no problem achieving your runtime and lumen goal and then some.