Spring Downunder car out for a drive but ??

[trevo]

Got the Roadster out gave it a wash then Wife and I head into the Port for coffee got 2ks slowly lost power switched the auxiliary electric pump on power back to normal same thing every 2k or so had coffee started perfect headed home (around 10 k) same thing every 2k.Have started it up over winter every few weeks, before I begin checking it out any ideas ??