Hmm... I have some info on it, but it's quite limited and vague... no specifics whatsoever..

By 1943, the Luftwaffe required fighters for high alt buff intercept role, which the A series of 190s weren't quite fit in. Thus, the new variants of 190s went into testing.
Fw 190B with BMW-801, Fw 190C with DB-603 and Fw 190D with Junkers Jumo-213. Of these only the Fw 190D series was fit for production and the B and C models were dropped due to variey of problems. In the case of Fw 190C, Kurt Tank himself personally prefered the DB-603 radial engine, but problems with production numbers of this particular engine kept it out of Tank's reach. Tank himself thought of the Jumo-213 as temporary solution until DB-603 production was back up.
It wasn't until Ta-152 that the DB-603 finally set its place with a 190 variant, which was by then too late.
That's all I know.. I'm sure other ppl will fill the gap
