All of a sudden my truck can't seem to maintain speed uphill when using cruise, it didn't use to have a problem at all. Its an automatic and whenever I was going uphill it would kick it into that 3rd passing gear and just go right up maintaining perfect speed. Now it only goes to that second passing gear (the one right after normal driving) and will lose speed so badly that if I don't hit the gas it will allow the truck to get 10 or more mph under what it's set to. Also, it seems to be idling slightly more rough, although the check engine light remains off, I presume it would turn on if it was misfiring. In addition to that, there is sometimes a gurgling sound like liquid bubbling coming from somewhere very near behind the dashboard, it does it often but especially when starting up (in any weather). I don't know if its related or not but thought I'd ask anyway, I'm no mechanic. Any advice would be greatly appreciated!!

 

gurgling sound is air in the heater core. probably unrelated to the cruise problem, but if you purge it and it keeps coming back, it indicates a leak. it might lead to overheating or poor heat, but thats another problem.

a bad TPS can cause lack of throttle response, as well as idle problems. its a common part from any store for $40-50. i'd replace that. if it solves your problem, discard your old TPS. if it doesn't, keep your old TPS as a spare.

 

any vacuum lines bad? that will affect the CC

 

Look at the vacuum line under the battery box for the cruise control malfunction. It's a common problem.

 

Have to agree with 95Ram on the vacuum line. .

 

+1 one at check all vacuum lines for cracks and such. That gurgling is air in the heater core. Just have to burp the air out of the system.

 

Cool much thanks guys, I'll definitely check those lines