I bought this 89 volvo 240, so far I have almost doubled the price of the car in the 2 months that I have owned it. It seems to be at least Idling good now and running good but has no real power to speak of when I accelerate. It seems to be worst after the engine is warm. I have replaced the fuel fiter, the orings on the injectors, tested the fuel pressure looks to manual specs. I replaced plus, and rotor and cap, and ohm tested plug wires, replaced timing belt and tensioner. It would run some what good for a while than the idle would get all funny and the engine would lack power,and then I pulled the spark plugs out and # 3 plug looked like it had black carbon all over it the other ones did not. I took the air intake hose off and found oil in the hose, I looked at the oil trap unit and found the drain hose in the engine block colapsed and the bottom 4 inches or so of the hose in the oil pan, so I replaced the oil trap and all the hoses.I have replaced temp gauge sensor and engine coolent temp sensor. I have replaced rpm sensor that mounts above flywheel. I have removed the intake manifold and throttle body and cleaned. I had replaced the air intake hose, checked the air filter box to make sure it workes right, and it does when it heats up. compression test showed all 4 around 160 psi.I have back probed the mass air sensor and the oxygen sensor, just looking for voltage numbers moving and there was, took the connector off the ECM to see if the temp sensor was reading to the connector and it was. The car seems to idle good now and run good but lacks power and very slow to accelerate. Tested the throttle switch and it meters like the manual says. The only codes I have had are 231, and 311. But no codes lately. My daughter owns a 91 240 and it has a lot of get up and go. I am not sure where to go any more. I have worked on this car 2 months solid and can not find the reason for its poor throttle response. I must be over looking some thing. I would sure appreciate any advice any one could offer. I was taken to the cleaners on this car, I bought it from a dealer and the guy knew exactly how to hide stuff and was a fast talker, I sent a week talking to him on the phone before I made my 500 mile trip to pick up the so called pursteen vehicle.Its been a night mare ever since, I have to much invested now to give up. I love my daughters car, I wish they still built vehicles like this today, they are a joy to work on compared to todays cars.