i have a 1993 dakota, it runs fine at start up when its cold but if i take it down the road and come back and engine is at engine operating temp, it will start idleing funnny. sometimes it will sit and jump from darn near dead to 1200 rmps. sometimes it will idle fine but when i step on the gas and let off when it comes down it will almost die and jump up to normal idle. some times it does die. i have put in a new fuel pump, fuel filter, new cap and rotor, new plugs and wires, new idle air control sensor. i thought maybe a vaccume leak but i couldnt find any and i thought if it was a vaccume leak it would idle rough even cold? wondering if its the throttle position???? i unhooked it and it ran even worse so i figured that was ok but got to thinking jus because i unhooked it and it ran worse does not mean it may not be the problem? anyone have any idea's at all im gettin tired of messing with it and i dont wanna go replacing stuff its getting expensive lol, and its just a work pickup nothing too special

thanks

 

It does sound like a vacuum leak. Any codes (besides the TPS since you probably tripped it by unpugging it)?

 

i checked codes awhile back but what came back wasnt exactly helping. how does a guy check codes again? turn key on and off 3 times ina row and count flashes?

 

checked codes this what i got (12 55) 12 was (from what i looked up anyway) Direct battery input to PCM was disconnected within the last 50 key-on cycles which i dont understand. and 55 was an ending to fault codes so that wasnt really a fault code. any idea's thanks