My new (used) Hangar 9 - Pulse XT60 - maiden flight on 05-07-17

I picked up a used Hangar9 - Pulse XT 60 in a trade. it is in good shape and has an OS .91FX engine on it. This has a wingspan of 70" and it flies really well.
This is my maiden flight on it, and then Jeremy takes it up for a spin.
On this maiden flight, everything went well.....After these two flights though, I started having trouble with the engine. - I flew it four more times, and had to make four dead-stick landings.
For some reason, the engine would run good for about 4 minutes, and then it would die. (usually when it went throttle up from a mid-level, but also when cruising at about 50% for a couple minutes without varying the throttle)
I am new to nitro engines, so if anyone has any ideas on what to check, let me know. (Jim, a very experienced pilot at our field, tried for about 30 minutes to get the engine tuned, but no luck with it - still dies after about 4 minutes of flight.)

[@mazpr2025]

No leaks in fuel line, no leaks in the engine, replace fuel lines and fuel tank, also glow plug. I had a similar issue, there was a small piece of rubber from the tank grommet which was a little bigger than the fuel line, it would clog randomly. On another engine it had a diry idle hole, on a OS .46.
Nice airplane, I may be getting one soon if numbers line correctly.

[@44Mag]

Thanks for the tips...This engine has a remote hi-speed needle valve and it felt "soft" when turning it. I ordered a replacement valve (about $19) and also replaced the gasket where the carb mounts to the manifold.
Once I did these two part changes, it has run just great....No issues with it staying running....(I probably could have just changed the o-ring that goes around the needle valve and got the same results, as the old needle looked fine. The o-ring was hard though, and I think it was leaking past it)
The plane is a great flyer. If you get one, you will like it a lot I think.