I have about 106000 miles on my truck and have replaced everything cheap i could but the fuel pump. My problem has been happening for 3 years and It never happens when i'm at the dealer. I will be sitting there and suddenly truck will start idling really rough and you smell gas and exhaust from under the hood and can hear a loud hissing like the iacv is doing something. I replaced the iacv and it never fixed my problem so now I am lost on what to do, it passes emission test with no problems. Had the injectors flushed etc. This will happen whether its cold or hot outside. I want to try and check for a vaccum leak but i forgot what to spray around the motor for it. I would post this on a truck site but I can't find any that are trustworthy like this site.  

I had a 94 s-10 that would intermittently bug out and not run right. It idled fine but wouldnt accelerate. Turned out to be the map sensor. They aren't very expensive and sounds like it could be causing your problem.  

Any idea if the map sensor can be returned if its not the problem? I can't really afford it right now cause I have 2 kids in diapers lol but if its the reason truck is messed up I need to try buying one lol. I would ask pepboys right now about returning it but im at work lol.  

I just had it happen again and I really kind of thing it could be the tps sensor now. After it stopped sputtering and i let off the brake it tried to accelerate pretty fast without my foot on the gas. I am still hoping its just something cheap to fix.  

what you might be hearing is the iacv opening to try to keep the idle speed up to specs..

but something else is failing...  without the year it makes it a little tougher for me ..

the EGR might be sticking open or be commanded wide open... that would slow the motor down causing the IACV to try to open wide...

the fuel pressure might be falling and leaning out the injector spray, this would also reduce the speed and cause the iacv to go wide open...      bad pump.. bad fuel pump relay, shorted wire..   junk in the fuel rail holding the fuel pressure regulator open....  did this start happening after a fuel filter change.?????? other causes for the loss of fuel pressure could be a worn out ignition switch.. (burned away contacts)

what year is it... so i can look it up easier.. and the 8th digit of the vin number..  

if it is 95 or earlier..  can you check the trouble codes by flipping the key on, off, on, off, on, off, on... within 10 seconds..   the check engine light will then flash 2 digit codes...   if there are no codes stored.. it will flash 5 times and then 5 times again...  

It is a 2000 model, i will try to get the vin on my break.  

I just read that if its the tps you can recalibrate it on some vehicles with no tools needed. just not sure how.  

do you have any friends with a real scan tool that reads live data????  OBDII....

intermittent problems are really hard to find.. without a scan tool... without a digital volt meter... without a vacuum gauge...  

Lol, no friends here. I haven't been in Dallas that long. The 8th digit is X if i am correct.  

so it is hard to decide which one is causing the problem... with out being hands on..


fuel pressure

egr

ecm

and a list of other things...

i think that you are really going to need somebody hands on...  

Well I tried taking off my tps just to check and it made a small rattling sound so I bought a new one. When I first put it on it was like the computer was learning from the new one or something. Now it seems to run fine but I won't know for at least another week if it starts idling rough since its just random.  

When the map was going out on my s-10 if i disconnected the electrical connector to it the truck ran fine. When the computer doesn't see input from a certain sensor a lot of times it will ignore it and find other ways to make decisions. Next time your truck acts up i would try disconnecting the map and see if it clears up.