Car looses power when it warms up

[Tancred]

I have a 1969 280sl which I have owned for 40 years.
Recently I have a problem that whilst driving, the car loses power,almost like fuel starvation. Switching off then restarting the engine solves the problem for a while. The situation repeats itself every three miles or so.
Any ideas on how to solve this problem? I have replaced fuel pump,coil,plugs,ht cables etc

[Bonnyboy]

Is the return line for fuel back into the fuel tank nice and clear?

[w113dude]

make sure all the filters are clean along the way, starting at the fuel tank then the main fuel filter. 

[Tancred]

Is the return line for fuel back into the fuel tank nice and clear?

I'll check it out

[ja17]

Good previous suggestions from Bonnyboy and w113dude.  Also check that the fuel tank  vent is clear.  Test it by removing the gas cap to solve the problem.