I've got a 2001 Grand Caravan 3.3 (150K miles) that hesitates and misfires intermittently between 1800 and 2200 RPM and intermittently at idle when in gear. When under load, the hesitation and misfire can be very pronounced (like pre-ignition), but it's only in that range. The only code it has ever thrown was a #2 cylinder misfire, and that was only on one occasion for a short time. Here's what I've done so far:

Replaced
Plugs
Wires
TPS
Idle Speed
Cam Position Sensor
Crankshaft Position Sensor
EGR valve
Fuel filter
Couple of "suspect" vacuum lines
O2 sensors (this past fall)

I've also run a bit of sea-foam through the tank and checked for compression and vacuum leaks. I have not checked for fuel pressure, nor have I checked injectors or coil pack (Fuel pump has been replaced within the past few years). Its been suggested I check for wiring harness shorts as well. Two other, possibly critical pieces of information-It seems to get worse with humidity and when the engine's warm. Also when I bleed the fuel system, I get air under pressure as well as fuel coming out the bleed valve. (if it were easy, I woudn't be posting it...)

 

Has it been doing this since the start when the fuel pump was replaced?

 

You know, I couldn't say. It seems to do this every winter and gets worse each year. I live in the pacific norrthwest, so winters are cold and rainy.

 

How about checking the fuel rail harness,I had the almost same problem replaced almost everything like u,Then i looked at the fuel rail harness I dont know how it ran at all all wires were melted together except 1!!!

 

Thanks for that tip, i just found this forum looking for the same problem and my injector harnes looks like crap. did you buy another one from the dealer or have it rewired??

 

I bought a new 1 a lot cheaper than buying from dealer!!!

 

Thanks for the info, looking into it now.

 

Caravanman, I will definitely look at the fuel rail harness; my son-in law told me something similar.

Max, you think the fuel pump might be a possibility?

 

Only because of the way you had written it above in your original post. It's worth getting a pressure tester and checking fuel pressure at the rail but I am thinking electrical now.

 

Inexpensive fix (instead of a new fuel injection harness) for a very common problem on these vans as they get older.

The 10 pin connector for the harness unplugs near the exhaust manifold on the drivers side.
The wires get brittle with age from the heat and can generate P020x & P030x code errors.

The Chrysler part number for the 10 pin connector harness repair kit is 05017114AA.
If you google for a price, use 05017114AA or drop the first zero and use 5017114AA.

The kit includes a new 10 pin connector, and the terminals are pre-crimped on 20 inches of wire.
It also comes with heat shrink, and some crimp connectors.

Also get some heat resistant loom to replace the original one that is falling apart.