Please help!

My truck hesitates at different speeds. It seems to happen most often when going up a hill. It has gotten worse in the last 3 weeks. Even on the freeway I have to gradually work my way up to 60 mph. When I attempt to speed up the motor hesitates, almost like it's missing. It's as if it's not getting enough fuel and/or spark.

I did a major tune up about 7 months ago: plugs, wires, cap, rotor, and all filters. I'm the original owner. The truck has been great, other than your basic B2200 lifter noise I've never had a problem with it.

I have 104K miles on the truck. I can't figure it out, any help would be greatly appreciated.

Here's what I've done (and not done) so far:
- air filter checks OK
- inspected all plugs (Bosch Platinums) 2 weeks ago - they all were burning great (haven't checked them recently though)
- replaced plug wires, didn't help
- replaced O2 sensor (aftermarket BOSCH), didn't help
- tried to check EGR valve but found out that I don't have one (damn Haynes mannual!)
- timing checked OK, timing belt was replaced at 60K miles
- fuel injectors never "professionally" cleaned
- need to inspect the fuel filter (which should be OK since it's only 7 months old)
- haven't checked the catalytic converter, unless its obvious, I imagine this would have to be done by a muffler shop?

Thanks so much!

Two things come to mind. I have a 91 carbed B2200 with a similar situation this week. Turned out to be the fuel filter, some of today's gas will clog them quickly. Easy diagnostic tool is when the hestitation occurs then ease up on throttle a bit and then accelorate through, if this works then fuel filter.\

If cat converter, when get home look under the truck if cat is red hot then it is plugged. Normally a plugged cat won't disappear.

Tim

I went to the parts store, the guy wanted $29 for the filter but he reccommended that I have the truck's fuel injection system cleaned since it's unlikely that a fuel filter would go bad after only 7 or 8 months.

$29 later I had clean injectors but the problem was still there. Since I was still at the shop, I had them run a diagnostic check on the truck. They found a bad plug that was miss-firing intermittently! They replaced the plugs and adjusted the timing, my truck runs GREAT again!

For a grand total of close to $200 altogether ($90 for O2 sensor - which needed to be replaced anyway, $29 for FI cleaning, $60 for dignostic/plugs/timing), the moral of the story is CHANGE THE DAMN PLUGS! It's worth it to spend less than $10 just to eliminate the plugs. These were BOSCH PLATINUMS, even they go bad! It's easy to miss a bad plug just by looking at it.

Other than normal maintenance, this is the most I've ever spent on this great little truck. The way I look at it is that it's a hell of a lot better than a car payment!!!!!!!

Good luck to all of you out there.