It was missing and jerking when accelerating so I replaced the plugs and wires because I discovered I had a burned ignition wire. All is well, no more jerking or missing. I drove it over 500 miles and started it the other day after stopping at the store for about five minutes and it started running similar to the way it had before. I checked all the plugs and wires. I had one loose plug so I removed it and examined it checked the gap and it was fine so I reinstalled it. Still runs bad. So I disconnected the ignition module and reconnected then restarted the truck. Well, now it runs worse than ever. I have no check engine light and this has me baffled. Could the diconnection of the ignition module have affected the timing in some way? Can you clean the connetions and plug ins on the ignition module, would it help? I can make most repairs myself, I just can't diagnose this one. Please Help.

 

disconnecting the ICM shouldnt have caused a problem. id be doing a fuel pressure test. check to see that you are in fact getting good fuel pressure then turn key back off and make sure that pressure doesnt drop within 5 minutes of the key being turned off. if it drops imediately it may be the fuel pressure regulator if you get no decent pressure at all i go with changin the fuel pump. im no expert but i just disconnected mu ICM on my 91 explorer XLT a fewweeks back to check the signal going to the crankshaft position sensor and after hookin it back up and reconnecting battery it wa running same as it did before. unless there is somthing very different about my 91 and your 98 id say the problem isnt because of disconnecting the ICM ,that doesnt mean itis notthe ICM that is malfunctioning though. hope you find the problem good luck..

 

just to add some omre info i read on another forum about these ICM problems and one thing that sounds like a strong possibility for you is the ICM not being grounded well. there was a guy on here talking about the way they were mounted they would get rusty around the mounting holes and screws where it is mounted to the body and lose ground. also with your probelms getting worse after disconnecting the ICM got me thinking maybe yours is a ground problem that was intensified when you pulled the harness lose from the ICM. id check it out maybe youll get lucky, if thats the problem sand down the rusty spots and pop it back on with some new screws or somthing. hope you get figured out!!