I've been searching this forum and I don't think I've found an answer to my problem yet, so thought I'd post.
My trouble is with a '99 GP with 140K miles. I think the behavior has been slowly progressing for the past year or so. It originally started out as a subtle surging while accelerating. Not noticeable to see on the tach and most people wouldn't have even felt it. As it was getting worse, you'd notice a loss in power when passing. It has now gotten to the point where, at times, I can't get over 45 MPH. It idles perfect and runs fine at low speed / RPM. When you accelerate, you can feel the engine being restricted somehow. In most cases when trying to get up to highway speed, it will run fine until you get in the neighborhood of 2K RPM, then it starts bogging. If you put your foot into the throttle, you can hear the engine laboring a little more, but it doesn't accelerate. If you can get to the point where it'll shift, it'll accelerate hard through the shift and run well until the RPM's come back up.
Where it gets tricky is that it won't throw codes and sometimes it will clear up and you can accelerate normally. As long as you stay at speed you're good, but if you stop, it will do usually do the same thing again.
Installed a new MAP sensor a couple months back, and just installed a new fuel filter. Checked the EGR valve for debris or blockage - looked good. Cleaned the MAF. Looked everything over on the top of the engine and used brake cleaner to search for vacuum leaks. Nothing.
Thought it could be a blocked CAT, but it doesn't make sense that the condition sometimes goes away briefly. Could be the MAF, but wouldn't it throw a code? Possibly the EGR, but again, wouldn't that throw a code too?
Any suggestions before randomly spending money on parts?
Thanks in advance,
Eric.
