e30 m40 318i Misfire

Hi can anyone advise me one the following Please:

For the past few days now i experience an intermittent misfire on my

1992 e30 has m40 318i engine

Have slightly noisy tappets for month or so...
Strangely it 'feels' like an 'electrical' misfire when i accelerate and then few seconds later, just takes off again..and then does it again later in the 'drive'

Could it also possibly be the fuel filter of fuel pump.

Any advice is valued

Thanks Theo