I'm gonna give it a full tune up and replace the pre cat o2 tomorrow morning and let you all know how that works.

 

I had the same problem on my 1998 truck. It was the throttle position sensor

 

Five year old thread..... to the day no less.

 

I have a 98 Dodge ram, that runs great until warmed up,then it has no acceleration,I've replaced both sensors ,I've replaced fuel pump, I've replaced water pump, and clutch fan, still kicking a 0505 code, so after inspecting harness replaced iac, cats don't seem to be clogged any insight would be greatly appreciated

 

Both sensors? Which sensors?

P0505 is iac control. That just controls idle...... do you have any idle issues?

 

I've ordered new iac, it was also kicking a 0132 which is o2 # 1 ,I have replaced both sensors, code went away still kicking the 505,iac.,because of a faulty clutch fan eng was running real hot,so I put a solid fan on as well as water pump,also just cleaned tcs,

 

I've ordered new iac, it was also kicking a 0132 which is o2 # 1 ,I have replaced both sensors, code went away still kicking the 505,iac.,because of a faulty clutch fan eng was running real hot,so I put a solid fan on as well as water pump,also just cleaned tcs,,but no idle issues,just when you go to drive it

 

Anyone ever get this figured out?

 

I know this is an old thread and I am a new member but thought it may help someone. Mine is a 1996 Dodge 3500, 5.9 gas. Idled fine, no misfiring but if I pushed the pedal to the floor it would misfire , pop back through throttle body and not pick up speed at all. If I let up on throttle it would go and drive normal as long as it was under half throttle. I did a complete tune up, replaced TPS, MAP, IAC, cleaned throttle body. Seemed like the more I did the worse it got. I had replaced the coil about 6 months ago but seen where someone else replaced their coil and it fixed theirs so I had nothing to lose and change mine and now it runs like new. Still surprised me but am very happy with it now. Don't assume new parts can't be bad.

 

So in reading all of these threads, we had the same issue. When the truck hit overdrive it hesitated. We were leaning towards the Cat. We put cat cleaner in the fuel tank and drove it for a while, We then changed the spark plugs and it seems to have fixed the issue. We have put a lot of work into this truck including a new PCM 6 months ago. Only thing that has not been changed is the block itself, gaskets and the cat. #8 plug was loose when we took it out. There has been no hesitation or stumbles. The only codes we had was P0420 (cat), p0455 evap leak large and p0442 small evap leak. Never a cylinder misfire. I hope this help someone else! Thanks y'all!