so after diagnosing my non-starter with help from this forum, i replaced the crankshaft sensor and yipee
however........... now the idle is 'hunting' (term my mechanic used?!) and sometimes misfiring. the revs start at 800 - 1500 jumping up and down and gradually work its way down to 800 and lower until it drops off completely and cuts out.
we've tried unplugging sensors but none make a difference.
if i press the accelerator the revs go up to the right amount but continue to jump up and down, same when i try to drive it (both times it cut out when i took my foot off the accelerator but started again straight away).
we have checked all leads, pipes etc.
can anyone please recommmend what we should do next to diagnose the cause?