if ur really interested in goin for econ phd, then i'd sugest u to join a 2 year taught msc at lse, havin a master frm ISI, u can easily land on eme program, keep in mind, no matter what u join, make sure it is 2 year and not 1!
i guess u can easily get into 2 year eme program wid TA position. keepin in mind ur masters, eme shud not be a VERY hard nut to crak, it shud not be abnormally challenging for u, as wid others wid bachelor degree.
havin said this, u can also consider applyn to oxford's mphil program, again a 2 year one.
im sure thes programs can take u to top 10 us econ depts.
man, i myself hav seen guys got placed in nyu, princeton and som other top-10 from ISI's MSQE program, wy not try that?
i hav seen guys sacrificed 5 years for joinin elite program, so, if u belev ur so determined to do elite program, then im sure u can make it wid ur isi master background, scores, gre, lors, etc,.