Starting issues

[Wibblyp]

So the story goes like this.
About a year ago me lass rings me and says she can't start the car-rover 114 MPi with 40k. I come home get in the car and it starts first time with no effort. Some 6 months later same thing. I accuse her of putting her foot on the accelerator whilst turning over-an argument ensues. Another 6 months goes by and yes, you've guessed it, same thing but this time,no matter what, it will not start.
New cap and rotor arm changed. The existing was original due to thread locked rotor and there was lots of corrosion. Still wouldn't start. Big dose of easy start and we're up and running. Off she goes. That evening she's saying that the engine is racing when changing up thru the gears. Initially thought throttle potentiometer so ordered a new one. In the mean time I changed the ht leads and drove it from Swindon to Bristol. It didn't miss a beat and the starting and racing fault has not occurred for over a week.
Am I missing something obvious or have the above cured the problems ?

[DotMatrix]

it can be a lot of things judging by your description. you dont really explain what the car does do when the key is turned? turns over? fires slightly? turns and fires but doesn't start?

[Wibblyp]

It would turn over fine until the battery went flat, it would sometimes half fire then not at all. Since the first post I've now thoroughly cleaned the Stepper motor and housing which was very coked up. I took it for a half hour drive last night and I was unable to get the engine to race. It started first time. If the problem doesn't rear it's head again, I'm thinking it was a number of issues. Mainly dizzy cap corroded and dirty stepper.

[Dave VVC]

Try looking at fuel pump and/or fuel reg, if the pump has a tiny bit of dirt in it, it wont run,
if the fuel reg is sticking, you wont get correct fuel pressure to start,
the reg should say '3 Bar' on it for the mpi.
fuel pressure when idling should be 2.5 Bar with vac hose on, and should go to 3 bar with the vac hose off.
you should hear the fuel pump 'pulse' on for @ 2 secs when keying on ign.

[Wibblyp]

Fuel pump checked and fine. Ihave subsequently cleaned the stepper motor again. There was a fair amount of carbon build up on the housing and the plunger. It is now running and starting sweetly. I am surprised however that such a build up would cause such a dramatic fault and can only hope the faults do not reoccur.
My advice to others who have a similar problem is the following,
Check for air leaks on hoses.
Check for any damage or obstruction in the throttle body.
Check and clean thoroughly the stepper, housing and plunger.
Check resistance of throttle potentiometer thru it's range.
Check fuel pump.

In my case I believe the stepper was at fault but hopefully others with more knowledge than myself will be able to explain that to me.
Happy New Year