The initial development of inhomogeneity upon stepwise cooling from the melt has been investigated in an elastomeric polypropylene (elPP), with isotactic and atactic blocks in the same chain. The simulation employs coarse-grained chains, with one bead for each repeating unit, on a high coordination lattice. Short-range intramolecular interactions are described by a rotational isomeric state model. Intermolecular interactions are derived from the behavior of pairs of molecules of propane in the gas phase. Analysis of the rates of equilibration of the simulations shows that there is sufficient time for local conformational relaxation at all temperatures studied from 298 to 473 K. However, at the lower temperatures there is insufficient time for the more extensive rearrangement of the chains required for development of the intermolecular interactions that would stabilize crystals of the isotactic blocks. Therefore the simulation is appropriate for the investigation of any heterogeneity that might develop before the onset of significant crystallization of the isotactic blocks. The fraction of C-C bonds in different rotational isomeric states changes very little over the temperature range covered. Intermolecular pair correlation functions have similar shapes when calculated for all beads, or for just those beads that appear in isotactic blocks. Nevertheless, there is greater heterogeneity in the elPP at 298 K than in isotactic polypropylene at the same temperature and thermal history. The heterogeneity of elPP can be detected by an analysis of the orientations of pairs of coarse-grained bonds and also from an analysis of the dynamics of individual beads. This heterogeneity of elPP, which appears before the onset of significant crystallization of the isotactic blocks, has contributions from individual 3(1) helices in the isotactic blocks and from strongly extended chain segments in those portions of the atactic blocks that are rich in racemo diads.