If it is a D-Jet Fuel Injection (either a 2.0L or 1.7L, come on man, throw us a bone here :-) then I would of course start with the ignition. Key points to check would be the ignition wires, but also check the timing, dwell, plug gap.
Next look at the FI, download the D-Jet article off the 914 fans web site
www.914fan.net/
I would guess, if it is a heat sensitve problem, the cylinder head temp sender.
Also look at the FI points in the bottom of the dizzy. While you're at it check and clean the FI ground points under the air distributor (intake manifold). These are the things that control two injectors at a time. I had a similar problem (long time readers are probably sick of hearing about it by now) that was traced to a bad inline resistor between the CHT and the brain.
If it is a L-Jet (1.8L) or a carb then still start with the ignition but after that I don't know, sorry.