I bought a 1995 Volvo 850 GLT for my daughter earlier this year. Overall the car runs great. But it ran sluggish and stumbled a lot at first.
The first thing I did was clean out the intake system and cleaned the MAF with MAF cleaner (what else?). I also replaced the air filter and rigged the thermostate in the airbox to be open all the time. This made things run much better, but the car still had some hesitation at times.
Next I replaced the cap and rotor and it ran even better. But still I get a hesitation. It seems to crop up when you accellerate out of a corner after coasting into it.

There is no CEL and no codes stored. When we first got the car there were two codes stored A1 114 (Program selector open circuit or short circuit to supply) and A7 123 (Engine coolant temperature from ignition cotrol module missing or faulty). The only thing I did with either of these faults is clean the contacts on the ECT.

I have checked the Throttle position sensor using on board diagnostics. It does recognize changes from WOT and Idle.

I have also done a lot of research. I am thinking about what to do next. Spark plugs and wires? PCV system? something else? I am open to suggestions to fix the hesitation I described.
Thanks in advance!

 

When you did the cap and rotor, did you replace the spark plugs? I had the same issue on my 850 and the reason was because I was using non-copper (OEM) plugs. I swapped out the plugs for the OEM ones and the issue went away. I would recommend replacing the plugs with these. IF you don't want to go with OEM, then at least go with Champion Copper Plugs.

 

That was next on my list... as well as a little seafoam. I bought the plugs last night and strated to put them in. But... I was afraid to pull the plug wires off the plugs. My bmw has a special tool that is stored under the spark plug cover for removing the wires without damaging them. The Volvo had nothing. I tried a pretty good tug, and it didn't come off. Am I doing something wrong? Do I need special pliers for this?

 

The plugs should come straight off with a bit of elbow grease. No special tool required.

 

I changed the plugs. I was worried about ruining the wires, but it was fine.
The hesitation seems to be gone!
Also, there was a little bogging at throttle tip in which also has disappeared.
Old plugs wer Champion coppers and looked brown and dry when they came out.
New plugs are NGK V-power (copper). I was sooooo tempted to get the Iridium IX plugs, but I've heard of problems with platinum in 850's so I stuck with cheapie plugs.

 

Our 98 had a big problem with hesitation and stalling at stops and low speeds(ie foot off the pedal). Codes were generated that stated mixture too rich so, because this was happening at a low thottle I looked at ide air control valve (IAC) and then the thottle position sensor. last of all the MAF(it was the most expensive, I loath being a parts replacer but some time it's the only way forward). BINGO bought a new MAF and all is perfect. Cleaning the MAF doesn't help the heating circuit, it is a sensitive and precise element that should(I think) be looked at/replaced in vehicle of this vintage.

 

One thing I see a lot of folks forget to change as well is the fuel filter. You would be surprised how that can help as well. Glad to hear the issue is gone though