The cold start at the back of inlet can be removed and cleaned with petrol/carb cleaner. Try this before buying a new one.... You say it idles upto 900-1000 RPM, what are they when you start the engine up?

Idle set up is from 850RPM and can be set to idle from that to 1250RPM, Does your instrument cluster gauge still have the factory fit black gauge? If so you'll see 2 little white dots to set the idle between..

Have you cracked opened the banjo bolts on the metering unit to see if fuel is getting to the unit? see above post for info as these do need regular maintenance, It looks like the car hasnt been touched for ages.

It doesn't appear that you've fit a new dizzy cap/rotor arm, leads spark plugs. Look over all service items aswell(you'll be wanting it serviced before using it anyway).

Check all jubilee clips are tight for all boost hoses.

Finally you might be having problems as that throttle cable is routed completely wrong, and its been bodged up completely wrong at the throttle housing end. How much play do you have in the cable at the pedal?