I've been running through all of the wiring on a 1990 Esprit SE, and found a secondary injector resistor (part A082M6442F) with familial resemblance to a depleted kipper tin, soldering iron scorch marks aside. I wonder what the original story was? I think this accounts for stumbling in upper RPMs.
It looks like there was an effort to reattach one of the resistor leads, but it's all been left open, and the resistor's ceramic case has crumbled. A kind correspondent on the TurboEsprit mailing list tells me that this should be directly replaceable by a 10 Watt, 3.3 Ohm resistor. In the US, Digikey has these for $.81 at https://www.digikey.com/product-detail/en/yageo/SQP10AJB-3R3/3-3W-10-ND/18723