The car starts with a little love and idles at about 3k until it’s warm. Then it gets stuck at around 1.5k. It revs fine and sounds smooth at upper mid and high rpm. Once it’s in gear it struggles to run and barely moves. I feather the gas and it’ll go, but slowly backfiring and chugging. Once it’s going in the mid to high rpms it’s fine. Have to shift into neutral at a stop or it’ll die. Replaced the distributor wires plugs and tps. No love. Gets fuel fine, the exhaust smells really rich. Smells like burnt toast and paper by the drivers side door, but no smoke and nothing looks or feels hot or burnt under the hood. It is leaking air somewhere around the intake manifold but I can’t tell where or how bad. You can hear air moving. Also has a cold air intake with a spectre cone. Please help me. I have tried everything I can think of. My mechanic next door couldn’t figure it out either but he also only works on primarily trucks and Chevy parts.