As a programme manager I’d start off looking at all the work streams and getting the PMs in to give their view of things on each of their projects but assume most of this is either deliberate bullshit or they’re repeating (unknowingly) bullshit fed to them by the implementation team.
Look for the projects that are succeeding and find out why (PM? size? implementation team? lack of scope creep?) and see if you can spread those to the other projects.
Is the programme failing on budget or delivery times (or both)?
IME programme managers have very little influence on the individual projects, other than prioritising resources at a more strategic level – sadly though that prioritisation is all too often to satisfy short-term client demands rather than help the programme long-term.
I work on the implementation side of ICT projects and IME the problem ones are where the implementation teams aren’t engaged early enough (if you set budgets and timescales without talking to us then you’ll, at best, get a version of the project that fits in with those constraints – rather than what the client actually needs).
Oh and make sure the client requirements are clear for each project – one project I was on went back to re-design phase a couple of weeks back after they realised it was pointless implementing something without a clear set of requirements from the client (we pointed this out months back but it was ignored as the client wanted ‘something’ urgently)