IML: 1981 Issues

I have a 1981 Imperial with 32,500 miles on it and have been for the last year restoring it to full running condition. The car was parked in 1987 with a full tank of gas in a very dry warehouse and sat there until last summer. I have had the tank boiled out replaced the in tank pump and pickup, resealed the engine including the intake gaskets, replaced the oil pump and pickup screen, it was plugged and at $25 for a new melling oil pump I replace the old one while i was there. I now also has a new set of BFgoodrich T/As RWLs. I also just removed the OEM plugs, wires and cap, all rubber hoses ( it still has the OEM fan belts on it at this point) and repacked the front wheel bearings. The car for the most part runs great and drives like new but upon restarting the car it runs like s**t and stalls untill still it to the floor and wind it up on the highway for a couple of miles and then it seems to be back to normal. This car has the OEM EFI and I do have extra electronics and high pressure pump to swap out (been raiding the salavage yards for a year)So the questions are, any idea how to deal with this or is this normal for the EFI cars ? Also I am considering replacing the OEM exhaust with duals loosing the cats (we have no emissions testing here). Will the duals work ok with the EFI ? Last but not least anyone have an Idea where I can get a tan cloth or leather seats for the Imperial. Specs on the car 3rd owner 1981, 32,500 miles 318 EFI, Black, Power Sunroof, Snowflake wheels w/red Imperial centers, No rust.