bigpaw

Anyone know what would cause this problem both hot and cold? When the key is turned, starter cranks two or three times then the engine starts very violently...like an explosion. When cold, it idles up to about 1300 - 1400 rpm normally and then gets to 950 or whatever when warmed up. Runs normally on street and highway with good acceleration and has recently passed smog with no trouble.

Sometimes when hot it will start violently, sometimes not. When it is violent and really shakes the whole car, sometimes the idle stays really low at around 500 rpm and stumbles until revving but sometimes it is just fine and idles almost normally - the engine always has a random misfire when idling hot. Has misfire at all ranges while stationary. If given a little throttle while starting, it is usually smooth, but I don't know if revving at startup is that great.

Have replaced plugs, wires, cap, rotor. Have pulled and cleaned injectors and replaced injector seals. Checked fuel pressure - no leaks, good pressure regulator function. Replaced fuel filter. Have replaced all vacuum hoses and checked all VSVs and other vacuum components and found no leaks or anything unusual. Have checked EGR and have even tried blocking off egr completely at intake manifold pipe to rule out egr valve leak. Have replaced all timing components and set timing with strobe and connector shorted at test port. Set TPS per 4crawler method and/or FSM method. Tested TPS resistances. Cleaned throttle body and aux air valve with tps off. Adjusted valves at least 10 times at different settings hot/cold to see if that would help. Checked and tightened all exhaust system bolts and checked for leaks. Replaced O2 sensor with denso. Replaced thermostat and tested coolant temp sensor. Checked cold start injector function and tried to start without cold start injector plugged in. Have tried to richen fuel mixture at AFM. Checked AFM resistances. Tested Replaced motor mounts. Compression is 185 to 190 in all cylinders. Don't have any coolant oil mixing and have light carbon on all piston tops, so I don't think there is a head gasket problem. Don't have a knock sensor on 2WD.

Any help would be great.