It could be several things. I have a 1991 Lotus Esprit SE and if you have a cut-off battery switch installed ,which totally cuts the battery off like I do, I don't drive it every day. It does this to regain its ECM settings. The esprit is known for battery drainage because the delco system always being on. Have you tried Freescan it will show you the faults.
http://www.lotusespritworld.com/EGuides/EMaintenance/freescan.html Mine had a bad ECM because the previous owner was jumping the battery to start it and fried a few things . I bought a cross-referenced Delco one of ebay for $75 stuck in my chip and has worked fine ever since. Start with checking your fuel filter 1st. then check your throttle position sensor it could have come loose or dirty they become sticky on the return. It might need cleaning. Hope this helps?

Fuel filter,tune up,could be crankshaft sensor.