Ok guyz maybe some of you know a thing or two about cars. Got a problem, here it is tell me what you think, any help appreciated.

94 Acura Integra LS 140k miles, Misfirng, Bogging Down, Backfire as engine is getting warmer. When the engine is cold it will almost never do this. Usually after it's warmed up, on accelerating the engine will misfire like crazy. It does this the most in 2nd gear, starting about 2200 rpms, all the way up. The only way to make it stop is to let off on the throttle to about a eighth of the way down, then it will quit misfiring and regain it's power. But if I was to hit the gas hard again it would just start misfiring again. It does it in other gears as well but it is the most noticeable in 2nd. Another thing, If I do not let off of the throttle it will eventually just backfire. I have replaced the mass airflow sensor, fuel pump, plugs, rotor cap, plug wires, fuel filter and fuel p regulater. It is throwing no check engine light codes. I have taken it to different mechanics and I keep getting told different things, and to be honest I really do no want to just keep replacing parts until I eventually fix it. I was told that it is the crankshaft position sensor now, but before I go out and spend more money I would like some different opinions on it. Thanks for your time guys.