1990 Renault Kangoo struggles to accelerate then engine cuts out.

This is an a problem that has happened since my garage put chemical cleaner in the engine not sure if it is connected or not. The car seems to struggle to accelerate and then just cuts out. It happened as I said after took to garage for MOT and was told I had to put a cleaner in the engine as emissions were too high. Garage said firstly it was glow plugs then fuel filter. Both changed and problem happened again. Took back and said there was a screw loose to filter. Problem went away for about a month and has now returned and is getting worse.