I own this honda accord '90, 290,000 kms on it. I had a broken exhaust system for last 3 months and just had it replaced. Now it runs smoothly but after a while the engine starts to stall and gives a little backfire. My rpm goes down and it won't accelerate no matter how hard I press the gas padel. I have to press the gas padel on and off to keep driving and keep the rpm steady. After I shut off the engine I can smell a very strong odor, like a plastic burning.
First check your tune up (wires, cap and rotor) next yuo may be experiencing a fuel problem or even a blocked exhaust (I say this in case your exhaust was open and you accumulated some debris in there before you had it repaired( can be checked easily by applying a vacuum guage to the manifolld at idle and seeing if the values are correct)
Also a fuel guage can be hooked up to the fuel rail and raise the idle untill the problem occurs (no too high ; no more than 2500 is recommended) sometimes a coil or igniter can cause intermittint problems as well' Good luck and I hope I was a bit of help to you!