Is it getting enough fuel? I had a 307 1.6 diesel and it did something similar, turned out that there was a problem with the fuel flow.
307 has a high pressure diesel injector system and if it's clogged for any reason the engine does a dance.
3 of the 4 glow plugs were working so the regen wouldn't work, got lots of back pressure and at 1 point I thought the pistons were going to shoot out of the engine block. I did a full DAF clean and replaces the glow plugs (bitch of a job) and it ran sweet and smooth after that.
I have a 1994 peugeot 306 xsi and have a weird problem with my gauges
When i turn up my interior fan speed, my coolant temp goes up and my fuel gauge
I guess its something electrical but i dont really know