[KOIT]

Hy to everybody, I am new at this forum, but I am Volvo fan and would ask some advice!
So I am driving with 940 GLT 91' model 2.3 16 v 114kw already 3 years.
I have made to my car service list to every part and and replacement lis with prices and I must add
have spent cosiderable sum of money, during 3 years i have driven some 60000 km=almoust 40000 miles. But also I have made some modifications to my car also:
platinum Spliitfire spark plugs (very good products- fuel consumption lowered 3 litre/per 100 km in urban.
cat back modified-tuned exhaust system(SIMMONS)
powerchip in ECU-replaced the original chip
K&N washable panel filter.
Resonator instead katalysator
Actually after I changed the original chip to powerchip the idle revs. startred to cough,
I have changed the lambda also, it was universal now there was put original-BOSCH and it is little bit better, but it still jumps the rev needle.Is it associated to fuel quality?
And what would you suggest, to tune up my car still.
Does it help to put sport modified exhaust manifold instead original one?
Wide open to any suggestion?

 

[Tech]

I would say to start by cleaning your throttle body and Idle motor.That would be the first thing I would look at.If you do that and still have problems then check for a vaccum leak.